Laws of Software Engineering
lawsofsoftwareengineering.com
lawsofsoftwareengineering.com
There are few principle of software engineering that I hate more than this one, though SOLID is close.
It is important to understand that it is from a 1974 paper, computing was very different back then, and so was the idea of optimization. Back then, optimizing meant writing assembly code and counting cycles. It is still done today in very specific applications, but today, performance is mostly about architectural choices, and it has to be given consideration right from the start. In 1974, these architectural choices weren't choices, the hardware didn't let you do it differently.
Focusing on the "critical 3%" (which imply profiling) is still good advice, but it will mostly help you fix "performance bugs", like an accidentally quadratic algorithms, stuff that is done in loop but doesn't need to be, etc... But once you have dealt with this problem, that's when you notice that you spend 90% of the time in abstractions and it is too late to change it now, so you add caching, parallelism, etc... making your code more complicated and still slower than if you thought about performance at the start.
Today, late optimization is just as bad as premature optimization, if not more so.
It's particularly the kind of people who like to say "hur hur don't prematurely optimize" that don't bother writing decent software to begin with and use the term as an excuse to write poor performing code.
Instead of optimizing their code, these people end up making excuses so they can pessimize it instead.
Usually those people also have a good old whinge about the premature optimization quote being wrong or misinterpreted and general attitudes to software efficiency.
Not once have I ever seen somebody try to derail a process of "ascertain speed is an issue that should be tackled" -> "profile" -> fix the hot path.
Many things need to be optimized before you can easily profile them, so at this stage its already too late and your software will forever be slow.
That's because your boss will never in a 1000 years hire the type of dev who can do that. And even if you did, there will be team members who will fight those fixes tooth and nail. And yes, I have a very cynical view of some devs but they earned that through some of the pettiest behavior I have ever seen.
People write some code, test it, ship it, then get some ideas that its too slow and make it faster.
The nice thing about doing it with shipped code is you can actually measure where time is spent insyead of guessing.
Ascertain an issue is too late for bad software. The technical term is polishing a turd.
Not that what you're describing doesn't happen, people trying to make something irrelevant fast, but that's not the big problem we face as an industry. The problem is bad software.
There's too little appreciation today for a well designed system. And the "premature optimization" line is often used to justify not thinking about things because, hey, that's premature. Just throw something together.
I don't think anyone is arguing for zero planning but in terms of very general rules we can talk about on blogs and such, I would definitely advise people to "do more and think less" to paraphrase an old prussian general.
I would say overplanning is a much more common problem but the issues it causes tend to be much less noticeable than the occasional really exciting under planned project.
I'm actually considering, for the first time since 2013/14 when I worked on a Visual Studio extension, creating a piece of desktop software - and a piece of cross-platform desktop software at that. Given that Microsoft's desktop story has descended into a chaotic mishmash of somewhat conflicting stories, and given it will be a cold day in hell before I choose Electron as the solution to any problem I might have, most likely I will roll with Qt + Rust, or at least Qt + something.
20-odd years ago I might have opted for Java + Swing because I'd done a lot of it and, in fairness to Swing, it's not a bad UI toolkit and widget set. These days I simply prefer the svelte footprint and lower resource reuqirements of a native binary - ideally statically linked too, but I'll live with the dynamic linking Qt's licensing necessitates.
It is written in Rust.
Your users are not going to notice. Sure, it's faster but it's not focused on the problem.
I really encourage people to read the Donald Knuth essay that features this sentiment. Pro tip: You can skip to the very end of the article to get to this sentiment without losing context.
Here ya go: https://dl.acm.org/doi/10.1145/356635.356640
Basically, don't spend unnecessary effort increasing performance in an unmeasured way before its necessary, except for those 10% of situations where you know in advance that crucial performance is absolutely necessary. That is the sentiment. I have seen people take this to some bizarre alternate insanity of their own creation as a law to never measure anything, typically because the given developer cannot measure things.
Similar to the "code should be self documenting - ergo: We don't write any comments, ever"
My counterpoint: Code can be self-documenting, reality isn't. You can have a perfectly clear method that does something nobody will ever understand unless you have plenty of documentation about why that specific thing needs to be done, and why it can't be simpler. Like having special-casing for DST in Arizona, which no other state seems to need:
(Then, shortly afterward I also tried to find a new job, realized the entire industry had changed, and was fortunate enough to decide it wasn't worth the trouble.)
That's likely thanks to C which goes to great pains to not specify the size of the basic types. For example, for 64 bit architectures, "long" is 32 bits on the Mac and 64 bits everywhere else.
The net result of that is I never use C "long", instead using "int" and "long long".
This mess is why D has 32 bit ints and 64 bit longs, whether it's a 32 bit machine or a 64 bit machine. The result was we haven't had porting problems with integer sizes.
To be fair, though, I come up short on a lot of things comp sci graduates know.
It's why Andrei Alexandrescu and I made a good team. I was the engineer, and he the scientist. The yin and the yang, so to speak.
I've met very few folks who understand the overheads involved, and how extreme the benefits can be from avoiding those.
The sort of insane stuff I've seen on the dotnet repo where people are trying to tear apart the entire type system just because they think they've cracked some secret performance code.
You mean the .net compiler/runtime itself? I haven't looked at it, but isn't that the one place you'd expect to see weirdly low-level C# code?
If you ask a typical grad the size of a bool they will inevitably say one bit, but, CPUs and RAM, etc don't work like that, typically they expect WORD sized chunks of memory - meaning that the boolean size of one but becomes a WORD sized chunk, assuming that it hasn't been packed
And you have a frame with an operands stack where you should be able to store at least a 32-bit value. `double` would just fill 2 adjacent slots.
And references are just pointers (possibly not using the whole of the value as an address, but as flags for e.g. the GC) pointing to objects, whose internal structure is implementation detail, but usually having a header and the fields (that can again be reference types).
Pretty standard stuff, heap allocating stuff is pretty common in C as well.
And unlike C, it will run the exact same way on every platform.
Not to mention indirection costs, but that’s a different issue.
And yet even more of a fun time with porting pointer code was going from the various x86 memory models[0] to 32-bit. Depending on the program, the pain was either near, far, or huge... :-D
I suggested to him that he'd have a hard time finding any existing C code that ran correctly on it. After all, how are you going to write a byte to memory if you've only got 32 bit operations?
Anyhow, after 20 years of programming C, I took what I learned and applied it to D. The integral types are specified sizes, and 2's complement.
One might ask, what about 16 bit machines? Instead of trying to define how this would work in official D, I suggested a variant of D where the language rules were adapted to 16 bits. This is not objectively worse than what C does, and it works fine, and the advantage is there is no false pretense of portability.
The integer representation wasn't always two's complement in the early days of computing, so you couldn't even assume that. C++ only required integer representations to be two's complement as of C++20, since the last architectures that don't work this way had effectively been dead for decades.
In that context, an 'int' was supposed to be the native word size of an integer on a given architecture. A long time ago, 'int' was an abstraction over the dozen different bit-widths used in real hardware. In that context, it was an aid to portability.
Don't you mean Windows instead of Mac? Most Unix-like operating systems use LP64 while Windows uses LLP64.
If the number of bits isn't actually included right in the type name, then be very sure you know what you're doing.
The senior engineer answer to "How many bits are there in an int?" is "No, stop, put that down before you put your eye out!" Which, to be fair, is the senior engineer answer to a lot of things.
On the other, the right answer is 16 or 32. It's not the correct answer, strictly speaking, but it is the right one.
He stopped me an said he was just looking to see if I knew what an INT 3 was. He said few engineers he interviewed had any idea.
I haven't used a debugger much at work for years because it's all Docker (I know it's possible but lots of hoops to jump through, plus my current job has everything in AWS i.e. no local dev).
1) Most bugs are integration bugs. Whereby multiple systems are glued together but there’s something about the API contract that the various developers in each system don’t understand.
2) Most performance issues are architectural. Unnecessary round trips, doing work synchronously, fetching too much data.
Debuggers and profilers don’t really help with those problems.
I personally know how to use those tools and I do for personal projects. It just doesn’t come up in my enterprise job.
More like death by a thousand abstractions. Not that profilers will help you any more with that.
It should be to the greatest extent possible. Strive to write literate code before writing a comment. Comments should be how and why, not what.
> - ergo: We don't write any comments, ever"
Indeed this does not logically follow. Writing fluent, idiomatic code with real names for symbols and obvious control flow beats writing brain teasers riddled with comments that are necessary because of the difficulty in parsing a 15-line statement with triply-nested closures and single-letter variable names. There's a wide middle ground where comments are leveraged, not made out of necessity.
I know it may be hard for me to understand the need for writing in english what is obvious (to me) in code. I also know i have read a stupid amount of code.
My rule is simple, if the comment repeats verbatim the name of a variable declaration or function name, it has to go. Anything else we can talk about.
I'm still salty about that time a colleague suggested adding a 500 kb general purpose js library to a webapp that was already taking 12 seconds on initial load, in order to fix a tiny corner case, when we could have written our own micro utility in 20 lines. I had to spend so much time advocating to management for my choice to spend time writing that utility myself, because of that kind of garbage opinion that is way too acceptable in our industry today. The insufferable bastard kept saying I had to do measurements in order to make sure I wasn't prematurely optimizing. Guy adding 500 kb of js when you need 1 kb of it is obviously a horrible idea, especially when you're already way over the performance budget. Asshat. I'm still salty he got so much airtime for that shitty opinion of his and that I had to spend so much energy defending myself.
OR, perhaps its the case that different contexts have different levels of effort. Running a spike can be an important way to promote new ideas across an org and show how things can be done differently. It can be a political tool that has positive impact, because there's a lot more to a business than simply writing good code. However if your org is horrible then it can backfire in the way that was described. Maybe business are too aggressive and trample on dev, maybe dev doesn't have a spine, maybe nobody spoke up about what a fucking disaster it was going to be, maybe they did and nobody listened. Those are all organisational issues akin to an exploitable code base but embedded into the org instead of the code.
These issues are not the direct fault of the spike, its the fault of the org, just like the idiot that took your poorly formatted comment and put it on the front page of Vogue.
I mean I could take a toddlers tricycle and try to take it onto the motorway. Can we blame the toy company for that? It has wheels, it goes forward, its basically a car, right? In the same way a spike is basically something we can ship right now.
"You can't tell where a program is going to spend its time. Bottlenecks occur in surprising places, so don't try to second guess and put in a speed hack until you've proven that's where the bottleneck is."
Moreso, in my personal experience, I've seen a few speed hacks cause incorrect behavior on more than one occasion.
Parent is talking about building software that is inherently non-performant due to abstractions or architecture with the wrong assumption that it can be optimized later if needed.
The analogy is trying to convert a garbage truck into a race car. A race car is built as a race car. You don't start building a garbage truck and then optimize it on the race course. There are obvious principles and understanding that first go into the building of a race car, assuming one is needed, and the optimization happens from that basis in testing on and off the track.
Yeah like, NOT indexing any fields in a database, that'll become a problem very quickly. ;)
Which is pretty close to just saying "don't do anything unless you have a good reason for doing it."
Even 'grug brained' isn't about not thinking, it's about keeping capacity in reserve for when the shit hits the fan. Proper Grug Brain is fully compatible with Kernighan's Law.
I’m being a bit provocative here, just to make two points:
a) Software development back in the day, especially when it comes to service, reach, security, etc., was completely different from today. Black Friday, millions of users, SLAs, 24-hour service... these didn’t exist back then.
b) Because of so many conditions — some mentioned in point (a) - prematurity ends when the code is live in production. End.
In these domains, algorithm selection, and fine tuning hot spots pays off significantly. You must hit minimum speeds to make your application viable.
And as I point out, what Knuth was talking about in terms of optimization was things like loop unrolling and function inlining. Not picking the right datastructure or algorithm for the problem.
I mean, FFS, his entire book was about exploring and picking the right datastructures and algorithms for problems.
You are right about the origin of and the circumstances surrounding the quote, but I disagree with the conclusion you've drawn.
I've seen engineers waste days, even weeks, reaching for microservices before product-market fit is even found, adding caching layers without measuring and validating bottlenecks, adding sharding pre-emptively, adding materialized views when regular tables suffice, paying for edge-rendering for a dashboard used almost entirely by users in a single state, standing up Kubernetes for an internal application used by just two departments, or building custom in-house rate limiters and job queues when Sidekiq or similar solutions would cover the next two years.
One company I consulted for designed and optimized for an order of magnitude more users than were in the total addressable market for their industry! Of that, they ultimately managed to hit only 3.5%.
All of this was driven by imagined scale rather than real measurements. And every one of those choices carried a long tail: cache invalidation bugs, distributed transactions, deployment orchestration, hydration mismatches, dependency array footguns, and a codebase that became permanently harder to change. Meanwhile the actual bottlenecks were things like N+1 queries or missing indexes that nobody looked at because attention went elsewhere.
I was quite literally asked to implement an in-memory cache to avoid a "full table scan" caused by a join to a small DB table recently. Our architect saw "full table scans" in our database stats and assumed that must mean a performance problem. I feel like he thought he was making a data-driven profiling decision, but seemed to misunderstand that a full-table scan is faster for a small table than a lookup. That whole table is in RAM in the DB already.
So now we have a complex Redis PubSub cache invalidation strategy to save maybe a ms or two.
I would believe that we have performance problems in this chunk of code, and it's possible an in-memory cache may "fix" the issue, but if it does, then the root of the problem was more likely an N+1 query (that an in-memory cache bandaids over). But by focusing on this cache, suddenly we have a much more complex chunk of code that needs to be maintained than if we had just tracked down the N+1 query and fixed _that_
Yes. When I was a young engineer, I was asked to design something for a scale we didn’t even get close to achieving. Eventual consistency this, event driven conflict resolution that… The service never even went live because by the time we designed it, everyone realized it was a waste of time.
I learned it makes no sense to waste time designing for zillions of users that might never come. It’s more important to have an architecture that can evolve as needs change rather than one that can see years into the future (that may never come).
Not if your optimization for performance is some Rube Goldberg assemblage of microservices and an laundry list of AWS services.
If you follow SOLID, you'll write OOP only, with always present inheritance chains, factories for everything, and no clear relation between parameters and the procedures that use them.
The only part of SOLID that is perhaps OO-only is Liskov Substitution.
L is still a good idea, but without object-inheritance, there's less chance of shooting yourself in the foot.
SOLID approaches aren't free... beyond that keeping code closer together by task/area is another approach. I'm not a fan of premature abstraction, and definitely prefer that code that relates to a feature live closer together as opposed to by the type of class or functional domain space.
For that matter, I think it's perfectly fine for a web endpoint handler to make and return a simple database query directly without 8 layers of interfaces/classes in between.
Beyond that, there are other approaches to software development that go beyond typical OOP practices. Something, something, everything looks like a nail.
The issues that I have with SOLID/CLEAN/ONION is that they tend to lead to inscrutable code bases that take an exponentially long amount of time for anyone to come close to learning and understanding... Let alone the decades of cruft and dead code paths that nobody bothered to clean up along the way.
The longest lived applications I've ever experienced tend to be either the simplest, easiest to replace or the most byzantine complex monstrosities... and I know which I'd rather work on and support. After three decades I tend to prioritize KISS/YAGNI over anything else... not that there aren't times where certain patterns are needed, so much as that there are more times where they aren't.
I've worked on one, singular, one application in three decades where the abstractions that tend to proliferate in SOLID/CLEAN/ONION actually made sense... it was a commercial application deployed to various govt agencies that had to support MS-SQL, Oracle and DB2 backends. Every, other, time I've seen an excess of database and interface abstractions have been instances that would have been better solved in other, less performance impacting ways. If you only have a single concrete implementation of an interface, you probably don't need that interface... You can inherit/override the class directly for testing.
And don't get me started on keeping unit tests in a completely separate project... .Net actually makes it painful to put your tests with your implementation code. It's one of my few actual critiques about the framework itself, not just how it's used/abused.
[1] https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpris...
This should be the header of the website. I think the core of all these arguments is people thinking they ARE laws that must be followed no matter what. And in that case, yeah that won't work.
Even his "critique" of Demeter is, essentially, that it focuses on an inconsequential aspect of dysfunction—method chaining—which I consider to be just one sme that leads to the larger principle which—and we, apparently, both agree on this—is interface design.
SOLID isn't bad, but like the idea of premature optimization, it can easily lead you into the wrong direction. You know how people make fun of enterprise code all the time, that's what you get when you take SOLID too far.
In practice, it tends to lead to a proliferation of interfaces, which is not only bad for performance but also result in code that is hard to follow. When you see a call through an interface, you don't know what code will be run unless you know how the object is initialized.
The problem is that SOLID on its own does nothing for you. It's a set of (vague) rules, but not a full framework for how to design software. I would even argue that SOLID is actively harmful if used on its own.
Things like Clean Architecture and Domain-Driven Design are a lot closer to being true frameworks for software design, and a lot of their basic principles are actually really good (like the core of the application being made up of objects which perform calculations, validations and business rules with no side effects), but the complexity of those architectures is a problem in itself.
And, even aside from that, I think the industry in general reached a point where people decided that, principled object-oriented design is just not worth it. Why spend all this effort worrying about the software remaining maintainable for decades, when we could instead just throw together something that works, then IPO, then rewrite the whole thing once we have money.
I think the most important principle above all is knowing when not to stick to them.
For example if I know a piece of code is just some "dead end" in the application that almost nothing depends on then there is little point optimizing it (in an architectural and performance sense). But if I'm writing a core part of an application that will have lots of ties to the rest, it totally does make sense keeping an eye on SOLID for example.
I think the real error is taking these at face value and not factoring in the rest of your problem domain. It's way too simple to think SOLID = good, else bad.
L and I are both pretty reasonable.
But S and D can easily be taken to excess.
And O seems to suggest OO-style polymorphism instead of ADTs.
That's how I view it. You should design your application such that extension involves little modifying of existing code as long as it's not necessary from a behavior or architectural standpoint.
Decades in, this is the worst of all of them. Misused by laziness or malice, and nowhere near specific enough.
The graveyard of companies boxed in by past poor decisions is sprawling. And the people that made those early poor decisions bounce around field talking about their "successful track record" of globally poor and locally good architectural decisions that others have had to clean up.
It touches on a real problem, though, but it should be stricken form the record and replaced with a much better principle. "Design to the problem you have today and the problems you have in 6 months if you succeed. Don't design to the problems you'll have have next year if it means you won't succeed in 6 months" doesn't roll off the tongue.
One thing that came out of the no-sql/new-sql trends in the past decade and a half is that joins are the enemy of performance at scale. It really helps to know and compromise on db normalization in ways such as leaning on JSON/XML for non-critical column data as opposed to 1:1/children/joins a lot of the time. For that matter, pure performance and vertical scale have shifted a lot of options back from the brink of micro service death by a million paper cuts processes.
I also find it a bit annoying is that most people just make shit up about stuff that is "faster". Instead of measuring and/or looking at the compiled bytecode/assembly, people just repeat tribal knowledge about stuff that is "faster" with no justification. I find that this is common amongst senior-level people at BigCos especially.
When I was working in .NET land, someone kept telling me that "switch statements are faster" than their equivalent "if" statements, so I wrote a very straightforward test comparing both, and used dotpeek to show that they compile to the exact same thing. The person still insisted that switch is "faster", I guess because he had a professor tell him this one time (probably with more appropriate context) and took whatever the professor said as gospel.
Generally I've found that the penalty, even without contention, is pretty minimal, and it almost always wins under contention.
And if you aren't optimizing for time complexity, then it's probably an over-optimization. Even if switch was faster, how much are we gaining here? A microsecond?
But, I've had instances where I've turned reports from minutes to milliseconds because of some shit SQL or doing something crazy in a loop. That's the optimization that matters, IMO.
This doesn't make sense. Why is performance (via architectural choices) more important today than then?
You can build a snappy app today by using boring technology and following some sensible best practices. You have to work pretty hard to need PREMATURE OPTIMIZATION on a project -- note the premature there
Optimization of bandwidth-bound code is almost purely architectural in nature. Most of our software best practices date from a time when everything was computation-bound such that architecture could be ignored with few bad effects.
There were fewer available layers of abstraction.
Whether you wrote in ASM, C, or Pascal, there was a lot less variance than writing in Rust, JavaScript, Python.
If you are building something with similar practical constraints for the Nth time this is definitely true.
You are inheriting “architecture” from your own memory and/or tools/dependencies that are already well fit to the problem area. The architectural performance/model problem already got a lot of thought.
Lots of problems are like that.
But if you are solving a problem where existing tools do a poor job, you better be thinking about performance with any new architecture.
So a lot of code quality debates don’t matter for the typical enterprise app. While a dev spends their afternoon shaving off 100 nanoseconds in the hot path, a second developer on a deadline added a poorly thought out round trip that adds 800milliseconds.
This architectural problems are also more difficult to unwind later since they tend to have cascading effects.
Bunch of stuff is done for us. Using postgres having indexes correct - is not premature optimization, just basic stuff to be covered.
Having double loop is quadratic though. Parallelism is super fun because it actually might make everything slower instead of faster.
Thinking about the overall design, how its likely to be used, and what the performane and other requirements are before aggregating the frameworks of the day is mature optimization.
Then you build things in a reasonable way and see if you need to do more for performance. It's fun to do more, but most of the time, building things with a thought about performance gets you where you need to be.
The I don't need to think about performance at all camp, has a real hard time making things better later. For most things, cycle counting upfront isn't useful, but thinking about how data will be accessed and such can easily make a huge difference. Things like bulk load or one at a time load are enormous if you're loading lots of things, but if you'll never load lots of things, either works.
Thinking about concurrency, parallelism, and distributed systems stuff before you build is also pretty mature. It's hard to change some of that after you've started.
I want it in a t-shirt. On billboards. Everywhere :)
Anyone who has done optimization even a little knows that it isn't very difficult, but you do need to plan and architect for it so you don't have to restructure you whole program to get it to run well.
Mostly it's just rationalization, people don't know the skill so they pretend it's not worth doing and their users suffer for it.
If software and website were even reasonably optimized people could just use a computer as powerful as a rasberry pi 5 (except for high res video) for most of what they do day to day.
For example, in Java I usually use ConcurrentHashMap, even in contexts that a regular HashMap might be ok. My reasoning for this is simple: I might want to use it in a multithreaded context eventually and the performance differences really aren't that much for most things; uncontested locks in Java are nearly free.
I've gotten pull requests rejected because regular HashMaps are "faster", and then the comments on the PR ends up with people bickering about when to use it.
In that case, does it actually matter? Even if HashMap is technically "faster", it's not much faster, and maybe instead we should focus on the thing that's likely to actually make a noticeable difference like the forty extra separate blocking calls to PostgreSQL or web requests?
So that's the premature optimization that I think is evil. I think it's perfectly fine at the algorithm level to optimize early.
Make a (very) good argument, and suggest a realtistic path to change the whole codebase, but don't create inconsistency just because it is "better". It is not.
It makes no difference to the outside code.
2) Locks are cheap
3) I seriously doubt that the difference between a Map and a ConcurrentHashMap is measurable in your app
Which means that both, the comments on your PRs are irrelevant and you are still going too far in your thread-safety. So you are both wrong.
What you are right about is to focus on network calls.
ConcurrentHashMap has the advantage of hiding the locking from me and more importantly has the advantage of being correct, and it can still use the same Map interface so if it’s eventually used downstream somewhere stuff like `compute` will work and it will be thread safe without and work with mutexes.
The argument I am making is that it is literally no extra work to use the ConcurrentHashMap, and in my benchmarks with JMH, it doesn’t perform significantly worse in a single-threaded context. It seems silly for anyone to try and save a nanosecond to use a regular HashMap in most cases.
The work can be done in future to migrate to using ConcurrentHashMap when the feature to add multithreading support is added. There's no sense to add groundwork for unplanned, unimplemented features - that is premature optimisation in a nutshell.
I think you are conflating YAGNI and premature optimisation and neither apply in this case.
My point was that even if it is not optimal, there’s really no utility in bickering about it because it doesn’t really change anything. The savings from changing it to regular hashmap will, generously, be on the order of nanoseconds in most cases, and so people getting their panties in a bunch over it seems like a waste of time.
I don't blame Knuth, he's talking about focusing on micro-optimizations, but a lot of devs nowadays don't even care to get basic performance right.
This is too true. However, often you dont fully know the shape of the domain until you swing at it and fail.
I agree but I don't think this discredits the "premature optimisation is the root of all evil" thing, aside from the fact that it's a heavy exaggeration.
The trouble is, people read it as "don't optimise" which is an incredibly bad decision.
Especially in the data world though, I've seen lots of teams really struggle with problems caused by using technologies they don't need (normally spark or kubernetes or both) just because they might need them later.
I think that type of pitfall is what the original quote is warning against.
its my favorit quotes
premature optimization nowadays looks like choosing microservice when monolith can works just fine
I think a more useful mental model is of one-way versus two-way decisions (local optimizations can be applied later., the architecture has to be right from the start), as well as expected risks and payoffs.
`ripgrep` tool call on opencode added `--follow` override, which allowed to traverse symlinks. And you can imagine what happens when symlinks point to ancestors. My 9950x3D CPU had 100% load all the time until I did a bit of research and added config to forbid this on `rg` level.
So I'd refine it as "Premature optimization is the root of all evil. Blatant ignorance of it is even worse."
“A variable should mean one thing, and one thing only. It should not mean one thing in one circumstance, and carry a different value from a different domain some other time. It should not mean two things at once. It must not be both a floor polish and a dessert topping. It should mean One Thing, and should mean it all of the time.”
I worked as a janitor for four years near a restaurant, so I know a little bit about floor polishing and dessert toppings. This law might be a little less universal than you think. There are plenty of people who would happily try out floor polish as a dessert topping if they're told it'll get them high.
not used that often to displace water.
It definitely revealed a lot of falsehoods and stereotypes.
It probably won’t be up very long but it’s a classic.
I’m still waiting for the moment in the ice cream shop when I can ask them, “sugar or plain?” https://mediaburn.org/videos/sugar-or-plain/
I think that would be called a drug, not a desert topping.
Used to be, anyway. Modern alternatives are much better. It's still used as glue in wind instruments though.
Of course some of that osmosizes back via lisp and APL.
I've seen CompSci guys especially (I'm EEE background, we have our own problems but this ain't one of them) launch conceptual complexity into the stratosphere just so that they could avoid writing two separate functions that do similar things.
The goal ought to be to aim for a local minima of all of these qualities.
Some people just want to toss DRY away entirely though or be uselessly vague about when to apply it ("use it when it makes sense") and thats not really much better than being a DRY fundamentalist.
A common "failure" of DRY is coupling together two things that only happened to bear similarity while they were both new, and then being unable to pick them apart properly later.
Which is often caused by the "midlayer mistake" https://lwn.net/Articles/336262/
The tricky part is that sometimes "a new thing" is really "four new things" disguised as one. A database table is a great example because it's a failure mode I've seen many times. A developer has to do it once and they have to add what they perceive as the same thing four times: the database table itself, the internal DB->code translation e.g. ORM mapping, the API definition, and maybe a CRUD UI widget. The developer thinks, "oh, this isn't DRY" and looks to tools like Alembic and PostGREST or Postgraphile to handle this end-to-end; now you only need to write to one place when adding a database table, great!
It works great at first, then more complex requirements come down: the database gets some virtual generated columns which shouldn't be exposed in code, the API shouldn't return certain fields, the UI needs to work off denormalized views. Suddenly what appeared to be the same thing four times is now four different things, except there's a framework in place which treats these four things as one, and the challenge is now decoupling them.
Thankfully most good modern frameworks have escape valves for when your requirements get more complicated, but a lot of older ones[0] really locked you in and it became a nightmare to deal with.
[0] really old versions of Entity Framework being the best/worst example.
But the code I'm talking about is really adding the same thing in 4 different places: the constant itself, adding it to a type, adding it to a list, and there was something else. It made it very easy to forget one step.
There should often be two points of truth because having one would increase the coupling cost more than the benefits that would be derived from deduplication.
Yeah there are ways to avoid this and you need to strike balances, but sometimes you have to be careful and resist the temptation to DRY everything up 'cuz you might just make it brittler (pun intended).
Take the 5 Rings approach.
The purpose of the blade is to cut down your opponent.
The purpose of software is to provide value to the customer.
It's the only thing that matters.
You can also philosophize why people with blades needed to cut down their opponents along with why we have to provide value to the customer but thats beyond the scope of this comment
Partially correct. The purpose of your software to its owners is also to provide future value to customers competitively.
What we have learnt is that software needs to be engineered: designed and structured.
Making software is a back-of-house function, in restaurant terms. Nobody out there sees it happen, nobody knows what good looks like, but when a kitchen goes badly wrong, the restaurant eventually closes.
This is a very costly way of developing software.
I've been at organizations that don't think engineers should write tests because it takes too much time and slows them down...
The "who gives a shit, we'll just rewrite it at 100x the cost" approach to quality is very particular to the software startup business model, and doesn't work elsewhere.
If you write a lot of code, the odds of something repeating in another place just by coincidence are quite large. But the odds of the specific code that repeated once repeating again are almost none.
That's a basic rule from probability that appears in all kinds of contexts.
Anyway, both DRY and WET assume the developers are some kind ignorant automaton that can't ever know the goal of their code. You should know if things are repeating by coincidence or not.
My view is over-engineering comes from the innate desire of engineers to understand and master complexity. But all software is a liability, every decision a tradeoff that prunes future possibilities. So really you want to make things as simple as possible to solve the problem at hand as that will give you more optionality on how to evolve later.
The spectrum is [YAGNI ---- DRY]
A little less abstract: designing a UX comes to mind. It's one thing to make something workable for you, but to make it for others is way harder.
The key is to avoid the temptation to DRY when things are only slightly different and find a balance between reuse and "one function/class should only do one thing."
One of my favorite things as a software engineer is when you see the third example of a thing, it shows you the problem from a different angle, and you can finally see the perfect abstraction that was hiding there the whole time.
A callback to do the processing?
> a flag
Oh.
> Now... several arguments... probably just a few lines that get run for all the types
Yeah, that does tend to be where it leads when new parameters are thought of in terms of requesting special treatment, rather than providing more tools.
Yes, yes, "the complexity has to go somewhere". But it doesn't all have to get heaped into the same pile, or mashed together with the common bits.
Yes the initial HTML looked similar in these few places, and the resultant usage of the abstraction did not look similar.
But it took a very long time reading each place a table existed and quite a bit longer working out how to get it to generate the small amount of HTML you wanted to generate for a new case.
Definitely would have opted for repetition in this particular scenario.
Which maybe is also fine, I dunno :)
It can be quite hard to explain when a student asks why you did something a particular way. The truthful answer is that it felt like the right way to go about it.
With some thought you can explain it partly - really justify the decision subconsciously made.
If they're asking about a conscious decision that's rarely much more helpful that you having to say that's what the regulations, or guidelines say.
Where they really learn is seeing those edge cases and gray areas
Sort of like a real code of law.
Saying this is like saying 'pick the optimum point' without saying anything about how to find the optimum point. This cannot be a law, it is the definition of optimum.
Note that optimum point need not be somewhere in the middle or 'inside', like a maxima. The optimum point could very well be on an extreme of the domain (input variables space).
So much SWE is overengineering. Just like this website to be honest. You don't get away with all that bullshit in other eng professions where your BoM and labour costs are material.
Reading through the list mostly made me feel sad. You can't help but interpret these through the modern lens of AI assisted coding. Then you wonder if learning and following (some) of these for the last 20 years is going to make you a janitor for a bunch of AI slop, or force you into a coding style where these rules are meaningless, or make you entirely irrelevant.
Also notice how many of the so-called _software laws_ are actually statements about human behaviour and people-problems.
Confirmation bias, Dunning-Kruger Effect, Sunk-Cost Fallacy, Ringlemann Effect, Price's Law, Putt's Law, Conway's Law, Brook's Law, Peter Principle, Hanlon's Razor, Amara's Law...
Of the 59 "laws", only a small number are guiding principles specifically about planning and software.
Human behaviour is hard to change -- the same dysfunction can be seen everywhere. As a fundamental principle, you need to use the right/best tool for the job; you will know when you are using the wrong tool/solution because you'll spend a significant amount of time trying to correct/mask the unwanted consequences.
And if you enter a shop where many tools are wrong... consider going to work in a different shop.
More like the Bible of Software Engineering then
- Every website will be vibecoded using Claude Opus
This will result in the following:
- The background color will be a shade of cream, to properly represent Anthropic
- There will be excessive use of different fonts and weights on the same page, as if a freshman design student who just learned about typography
- There will be an excess of cards in different styles, a noteworthy amount of which has a colored, round border either on hover or by default on exactly one side of the card
"In analyzing complexity, fast iteration almost always produces better results than in-depth analysis."
Boyd invented the OODA loop.
And what a great and very subtle example with the fighter jet control sticks. This reminds of a build time issue I once had. Yeah, way back in college, did really poorly on a final programming project, because didn't realize you were supposed to swap out a component they had you write with a mock component that was provided for you - hard to explain, but they wanted you to write this component to show you could, but once you did, you weren't supposed to use it, because it was extremely slow to build. So they also gave you a mock version to use when working on the code of your main system.
Using my full component killed my build time, as it took 10 minutes to build instead of a few seconds, and it was the one school programming project I couldn't finish before the deadline and was super stressful. Was a very painful lesson but ever since have always found ways to shorten my build times.
I reserve the right to become smarter as I learn stuff. That means that I reserve the right to produce better designs as I learn stuff. Want me to produce better designs? Let me learn stuff. Therefore, let me iterate a few times.
...On reading more it seems of use primarily in adversarial situations, so not-so-much resonant.
If it can be slopped, it will be slopped.
(Wikipedia nerds often say "No, anyone can create a page as long as they follow the 137 guidelines!" This is a prank- Wikipedia admins will delete your article no matter how many guidelines it follows)
> "Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it"
I always liked the fence story better though.
Structure code so that in an ideal case, removing a functionality should be as simple as deleting a directory or file.
For example, each comment on HN has a line on top that contains buttons like "parent", "prev", "next", "flag", "favorite", etc. depending on context. Suppose I might one day want to remove the "flag" functionality. Should each button be its own file? What about the "comment header" template file that references each of those button files?
100_parent.template
150_context.template
200_prev_next.template
300_flag.template
350_favorite.template
Looks odd with the numbering, no?
But then you get the added benefit of being able to refer to them by numbers, just "100" or "300" without having to glue humanlang inflection, declension, punctuation onto identifiers that happen to be words...
Some places where you can see this pattern: BASIC's explicit line numbering; non-systemd init systems.
Imagine the code as a graph with nodes and edges. The nodes should be grouped in a way that when you display the graph with grouped nodes, you see few edges between groups. Removing a group means that you need to cut maybe 3 edges, not 30. I.e. you don't want something where every component has a line to every other component.
Also when working on a feature - modifying / adding / removing, ideally you want to only look at an isolated group, with minimal links to the rest of the code.
This in itself might not be enough to justify this, but the fewer files will lead to more challenges in a collaborative environment (I’d also note that more small files will speed up incremental compilations since unchanged code is less likely to get recompiled which is one reason why when I do JVM dev, I never really think about compilation time—my IDE can recompile everything quickly in the background without my noticing).
You got a point for incremental compilation. But fewer files (done well) is not really a challenge as everything is self contained. It makes it easier to discern orthogonal features as the dependency graph is clearer. With multiple files you find often that similar things are assumed to be identical and used as such. Then it’s a big refactor when trying to split them, especially if they are foundational.
Asking "who wrote this stupid code?" will retroactively travel back in time and cause it to have been you.
- Jeremy Clarkson (Top Gear, series 14 episode 5)
- Shirky Principle: Institutions will try to preserve the problem to which they are the solution
- Chesterton's Fence: Changes should not be made until the reasoning behind the current state of affairs is understood
- Rule of Three: Refactoring given only two instances of similar code risks selecting a poor abstraction that becomes harder to maintain than the initial duplication
> Fen's law: copy-paste is free; abstractions are expensive.
edit: I should add, this is aimed at situations like when you need a new function that's very similar to one you already have, and juniors often assume it's bad to copy-paste so they add a parameter to the existing function so it abstracts both cases. And my point is: wait, consider the cost of the abstraction, are the two use cases likely to diverge later, do they have the same business owner, etc.
> 11. Abstractions don’t remove complexity. They move it to the day you’re on call.
Then I committed the code and let the second AI review it. It too had no problem with goto's.
Claude's Law: The code that is written by the agent is the most correct way to write it.
"Every application has an inherent amount of irreducible complexity that can only be shifted, not eliminated."
I think it's more useful to remember when you're refactoring that if you try to make one bit of a system simpler then you often just make another part more complex. Why write something twice to end up with it being just as bad the other way round?
When it comes to frameworks (any framework) any jargon not explicitly pointing to numbers always eventually reduces down to some highly personalized interpretation of easy.
It is more impactful than it sounds because it implicitly points to the distinction of ultimate goal: the selfish developer or the product they are developing. It is also important to point out that before software frameworks were a thing the term framework just identifies a defined set of overlapping abstract business principles to achieve a desired state. Software frameworks, on the other hand, provide a library to determine a design convention rather than the desired operating state.
I had a hard time learning the whole mvc concept
Really great book even if don’t care about lisp or ai.
Marianne Bellotti's Kill It with Fire is a quick but good read
"The meta-law of software engineering: All laws of software engineering will be immediately misinterpreted and mindlessly applied in a way that would horrify their originators. Now that we can observe the behaviour of LLMs that are missing key context, we can understand why."
Or, you can't boil down decades of wisdom and experience into a pithy, 1 sentence quote.
People bring it up to argue for never thinking about performance, which flips the intent on its head. The real takeaway is that you need to spot that critical 3% early enough to build around it, and that means doing some optimization thinking up front, not none at all.
I think it is better to have real requirements like: The code needs to be testable in a simple way.
One who was a Python core developer and who knew many languages and could "compile in his head" what the result of some code will be in assembly. I would trust this one.
One, who criticized my C code for having multiple procedures, because that would make it look after more pointers and told me it would be better all in one long procedure, lol, without ever even considering the readability. That one was likely also simply wrong because of the compiler probably inlining things anyway. That one taught a math lecture and used C. Needless to say I wouldn't trust that one when it comes to writing good code.
Then I had a math physics guy, who wrote Java 5 or earlier code when it was Java 8 times. That one didn't use generics at all, and cast to Object instead and whatever else. He also explained, that he uses bit shift in a for loop variable update, because that was faster than *2. Yeah, also wouldn't trust that one to give any advice on how to write good code. It taught me to be very skeptical of mathematicians writing code, unless they have a proven track record of software development skills. This kind of person is the reason why mathematicians and physicists should be supported by an actual software developer, to write their code, and not be too ignorant or arrogant to consider hiring one.
I also had one professor, who taught a math lecture in such a bad way, that it was hard to follow and even his writing on the blackboard was illegible. That one also had another lecture which was mostly talk about Internet and web concepts in one of the most grating accents imaginable, almost comical. I wouldn't trust that one to give advice on writing good code.
There's no system, it's five rules selected at random.
Worse, their usefulness varies from hopelessly vague through trivial to actively confusing.
The I and O of solid are fine and don’t cause too many problems.
But I agree that Dependency Inversion is a recipe for loads of pointless interfaces that are only ever used once. I strongly prefer the traditional pattern where high level modules depend on lower level modules, it’s much simpler.
I think it would be better as SOIL not SOLID.
Maybe they could have replaced the D with DRY…
> Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.
Anyway, the list seems like something AI scraped and has a strong bias towards "gotcha" comments from the likes of reddit.
9. Most software will get at most one major rewrite in its lifetime.
This one is listed as design, but it could just as easily count as architecture. Guessing a lot developers have worked on scaling with lambda functions or a complex IAC setup when a simple API running on a small VPS would have done the trick, at least until enough people are using the application for it to be considered profitable.
OPS gave me shit about it, and I was like kiss my ass, the cluster costs EXACTLY the same and deployments are 25% faster.
I think people forget that in the cloud, bigger servers don't really cost more until you get crazy about it.
Or develop a skill to make it correct, fast and pretty in one or two approaches.
- Write a correct, pretty implementation
- Beat Claude Code with a stick for 20 minutes until it generated a fragile, unmaintainable mess that still happened to produce the same result but in 300ms rather than 2500ms. (In this step, explicitly prompting it to test rather than just philosophising gets you really far)
- Pull across the concepts and timesaves from Claude's mess into the pretty code.
Seriously, these new models are actually really good at reasoning about performance and knowing alternative solutions or libraries that you might have only just discovered yourself.
But yes, the scope and breadth of their knowledge goes far beyond what a human brain can handle. How many relevant facts can you hold in your mind when solving a problem? 5? 12? An LLM can take thousands of relevant facts into account at the same time, and that's their superhuman ability.
(~150) is the size of a community in which everyone knows each other’s identities and roles.
In anthropology class. You can ask someone to write down the name of everyone they can think of, real or fictional, live or dead and most people will not make it to 250.
Some individuals like professional gossip columnists or some politicians can remember as many as 1,000 people.
complexity(system) =
sum(complexity(component) * time_spent_working_in(component)
for component in system).
> complexity is not a function of time spent working on something.
But the complexity you observe is a function of your exposure to that complexity.
The notion of complexity exists to quantify the degree of struggle required to achieve some end. Ousterhout’s observation is that if you can move complexity into components far away from where you must do your work to achieve your ends, you no longer need to struggle with that complexity, and thus it effectively is not there anymore.
That’s pretty much what good design is about. Your solve a foundational problems and now no one else needs to think about it (including you when working on some other parts).
No, it’s a win, even then.
Say you are writing an operating system, and one of the fundamental data structures you use all over the place is a concurrency-safe linked list.
Option 1 is to manipulate the relevant instances of the linked list directly—whenever you need to insert, append, iterate over, or delete from any list from any subsystem in your operating system. So you’ll have low-level list-related lock and pointer operations spread throughout the entire code base. Each one of these operations requires you to struggle with the list at the abstraction level and at the implementation level.
Option 2 is to factor out the linked-list operations and isolate them in a small library. Yes, you must still struggle with the list at the abstraction and implementation levels in this one small library, but everywhere else the complexity has been reduced to having to struggle with the abstraction level only, and the abstraction is a small set of straightforward operations that is easy to wrap your head around.
The sole difference between the options, as you wrote, is that “the complexity just migrates to another location.” But which would you rather maintain?
That was Ousterout’s point.
I actually had a college run over by a bus on the way to work in London, was very lucky and made a full recovery.
Head poking out under the main exit of the bus.
Sure, don't add hooks for things you don't immediately need. But if you are reasonably sure a feature is going to be required at some point, it doesn't hurt to organize and structure your code in a way that makes those hooks easy to add later on.
Worst case scenario, you are wrong and have to refactor significantly to accommodate some other feature you didn't envision. But odds are you have to do that anyway if you abide by YAGNI as dogma.
The amount of times I've heard YAGNI as reasoning to not modularize code is insane. There needs to be a law that well-intentioned developers will constantly misuse and misunderstand the ideas behind these heuristics in surprising ways.
Where's Chesterton's Fence?
https://en.wiktionary.org/wiki/Chesterton%27s_fence
[EDIT: Ninja'd a couple of times. +1 for Shirky's principle]
A couple are well-described/covered in books, e.g., Tesler's Law (Conservation of Complexity) is at the core of _A Philosophy of Software Design_ by John Ousterhout
https://www.goodreads.com/en/book/show/39996759-a-philosophy...
(and of course Brook's Law is from _The Mythical Man Month_)
Curious if folks have recommendations for books which are not as well-known which cover these, other than the _Laws of Software Engineering_ book which the site is an advertisement for.....
Applies to opensource. But it also means that code reviews are a good thing. Seniors can guide juniors to coax them to write better code.
That one's free.
As JFK never said:
“””We do these things, not because they are easy,
But because we thought they would be easy”””
I wish AWS/Azure had this functionality.
Especially things like “every system grows more complex over time” — you can see it in almost any project after a few iterations.
I think the real challenge isn’t knowing these laws, but designing systems that remain usable despite them.
* https://martynassubonis.substack.com/p/5-empirical-laws-of-s...
* https://newsletter.manager.dev/p/the-unwritten-laws-of-softw..., which linked to:
* https://newsletter.manager.dev/p/the-13-software-engineering...
While browsing it, I of course found one that I disagree with:
Testing Pyramid: https://lawsofsoftwareengineering.com/laws/testing-pyramid/
I think this is backwards.
Another commenter WillAdams has mentioned A Philosophy of Software Design (which should really be called A Set of Heuristics for Software Design) and one of the key concepts there are small (general) interfaces and deep implementations.
A similar heuristic also comes up in Elements of Clojure (Zachary Tellman) as well, where he talks about "principled components and adaptive systems".
The general idea: You should greatly care about the interfaces, where your stuff connects together and is used by others. The leverage of a component is inversely proportional to the size of that interface and proportional to the size of its implementation.
I think the way that connects to testing is that architecturally granular tests (down the stack) is a bit like pouring molasses into the implementation, rather than focusing on what actually matters, which is what users care about: the interface.
Now of course we as developers are the users of our own code, and we produce building blocks that we then use to compose entire programs. Having example tests for those building blocks is convenient and necessary to some degree.
However, what I want to push back on is the implied idea of having to hack apart or keep apart pieces so we can test them with small tests (per method, function etc.) instead of taking the time to figure out what the surface areas should be and then testing those.
If you need hyper granular tests while you're assembling pieces, then write them (or better: use a REPL if you can), but you don't need to keep them around once your code comes together and you start to design contracts and surface areas that can be used by you or others.
My bet is on the long arc of the universe trending toward complexity... but in spite of all this, I don't think all this complexity arises from a simple set of rules, and I don't think Gall's law holds true. The further we look at the rule-set for the universe, the less it appears to be reducible to three or four predictable mechanics.
Gall notes that the universe naturally trends toward complexity and unintended consequences and therefore complex designs should be assumed to already be full of these unintended consequence “bugs”. He proposes that systems should be designed:
- with less scope to reduce unintended consequences,
- with less rigidity to allow for workarounds when unintended consequences arise, and
- to take advantage of “momentum” to reduce the required energy to use the system correctly. In other words make the right thing the easy thing, remembering that the easiest thing to do is nothing, thus systems will halt if operators get too busy with other tasks.)
- Not realizing it's a very concrete theorem applicable in a very narrow theoretical situation, and that its value lies not in the statement itself but in the way of thinking that goes into the proof.
- Stating it as "pick any two". You cannot pick CA. Under the conditions of the CAP theorem it is immediately obvious that CA implies you have exactly one node. And guess what, then you have P too, because there's no way to partition a single node.
A much more usable statement (which is not a theorem but a rule of thumb) is: there is often a tradeoff between consistency and availability.
I pulled those notes into a browsable site with 56 laws, grouped into categories, with short explanations and separate pages for each one.
The goal was simple: put these ideas in one place, so when you want a quick refresher on Conway’s Law, Brooks’s Law, Gall’s Law, Hyrum’s Law, or Goodhart’s Law, you can find it fast.
I’m more interested in criticism than praise. Which laws are missing, which ones feel overstated, and which ones get misused most often in real work?
Wow, that is incredibly sad to hear. I'm 40+ years in, and still love all of that.
https://lawsofsoftwareengineering.com/laws/premature-optimiz...
It leaves out this part from Knuth:
>The improvement in speed from Example 2 to Example 2a is only about 12%, and many people would pronounce that insignificant. The conventional wisdom shared by many of today’s software engineers calls for ignoring efficiency in the small; but I believe this is simply an overreaction to the abuses they see being practiced by penny-wise- and-pound-foolish programmers, who can’t debug or maintain their “optimized” programs. In established engineering disciplines a 12% improvement, easily obtained, is never considered marginal; and I believe the same viewpoint should prevail in software engineering. Of course I wouldn’t bother making such optimizations on a one-shot job, but when it’s a question of preparing quality programs, I don’t want to restrict myself to tools that deny me such efficiencies.
Knuth thought an easy 12% was worth it, but most people who quote him would scoff at such efforts.
Moreover:
>Knuth’s Optimization Principle captures a fundamental trade-off in software engineering: performance improvements often increase complexity. Applying that trade-off before understanding where performance actually matters leads to unreadable systems.
I suppose there is a fundamental tradeoff somewhere, but that doesn't mean you're actually at the Pareto frontier, or anywhere close to it. In many cases, simpler code is faster, and fast code makes for simpler systems.
For example, you might write a slow program, so you buy a bunch more machines and scale horizontally. Now you have distributed systems problems, cache problems, lots more orchestration complexity. If you'd written it to be fast to begin with, you could have done it all on one box and had a much simpler architecture.
Most times I hear people say the "premature optimization" quote, it's just a thought-terminating cliche.
I wholeheartedly agree with you here. You mentioned a few architectural/backend issues that emerge from bad performance and introduce unnecessary complexity.
But this also happens in UI: Optimistic updates, client side caching, bundling/transpiling, codesplitting etc.
This is what happens when people always answer performance problems with adding stuff than removing stuff.
- The customer is always right in matters of taste
- Jack of all trades, master of none, but oftentimes better than a master of one
- Curiosity killed the cat, but satisfaction brought it back
- A few bad apples spoil the barrel
- Great minds think alike, though fools seldom differ
Even "pull yourself up by your bootstraps" was originally meant to highlight the absurd futility of a situation.
Just a little historic context will tell you what Knuth was talking about.
Compilers in the era of Knuth were extremely dumb. You didn't get things like automatic method inlining or loop unrolling, you had to do that stuff by hand. And yes, it would give you faster code, but it also made that code uglier.
The modern equivalent would be seeing code working with floating points and jumping to SIMD intrinsics or inline assembly because the compiler did a bad job (or you presume it did) with the floating point math.
That is such a rare case that I find the premature optimization quote to always be wrong when deployed. It's always seems to be an excuse to deploy linear searches and to avoid using (or learning?) language datastructures which solve problems very cleanly in less code and much less time (and sometimes with less memory).
Separately, I'd add Rust's API design principles, though it's more of a adjunct with things in common. https://gist.github.com/mjball/9cd028ac793ae8b351df1379f1e72...
Look, I understand the intent you have, and I also understand the frustration at the lack of care with which many companies have acted with regards to personal data. I get it, I'm also frustrated.
But (it's a big but)...
Your suggestion is that we hold people legally responsible and culpable for losing a confrontation against another motivated, capable, and malicious party.
That's... a seriously, seriously, different standard than holding someone responsible for something like not following best practices, or good policy.
It's the equivalent of killing your general when he loses a battle.
And the problem is that sometimes even good generals lose battles, not because they weren't making an honest effort to win, or being careless, but because they were simply outmatched.
So to be really, really blunt - your proposal basically says that any software company should be legally responsible for not being able to match the resources of a nation-state that might want to compromise their data. That's not good policy, period.
What we don't do in engineering is hold the engineer responsible when Russia bombs the bridge.
What you're suggesting is that we hold the software engineer responsible when Russia bombs their software stack (or more realistically, just plants an engineer on the team and leaks security info, like NK has been doing).
Basically - I'm saying you're both wrong about lacking standards, and also suggesting a policy that punishes without regard for circumstance. I'm not saying you're wrong to be mad about general disregard for user data, but I'm saying your "simple and clear" solution is bad.
... something something... for every complex problem there is an answer that is clear, simple, and wrong.
France killed their generals for losing. It was terrible policy then and it's terrible policy now.
No. Not the company, holding companies responsible doesn't do much. The engineer who signed off on the system needs to be held personally liable for its safety. If you're a licensed civil engineer and you sign off on a bridge that collapses, you're liable. That's how the real world works, it should be the same for software.
These kinds of failures are not inevitable. We can build sociotechnical systems and practices that prevent them, but until we're held liable--until there's sufficient selection pressure to erode the "move fast and break shit" culture--we'll continue to act negligently.
It seems like your issue is that we don't hold all companies to those standards. But I'm personally ok with that. In the same way I don't think residential homes should be following commercial construction standards.
That doesn't worry me overly much.
> What do you think SOC 2 type 2 and ISO 27001 are?
They're compliance frameworks that have little to no consequences when they're violated, except for some nebulous "loss of trust" or maybe in extreme cases some financial penalties. The problem is the expectation value of the violation penalty isn't sufficient to change behavior. Companies still ship code which violates these things all the time.
> It seems like your issue is that we don't hold all companies to those standards.
Yes, and my issue is that we don't hold engineers personally liable for negligent work.
> I don't think residential homes should be following commercial construction standards.
Sure, there are different gradations of safety standards, but often residential construction plans require sign-off by a professional engineer. In the case when an engineer negligently signs off on an unsafe plan, that engineer is liable. Should be exactly the same situation in software.
Ex - MMG for 2026 was prosecuted because:
- They failed to notify in response to a breach.
- They failed to complete proper risk analysis as required by HIPAA
They paid 10k in fines.
It wasn't just "They had a data breach" (ops proposal...) it was "They failed to follow standards which led to a data breach where they then acted negligently"
In the same way that we don't punish an architect if their building falls over. We punish them if the building falls over because they failed to follow expected standards.
Relax. You will make all the mistakes because the laws don't make sense until you trip over them :)
Comment your code? Yep. Helped me ten years later working on the same codebase.
You can't read a book about best practises and then apply them as if wisdom is something you can be told :)
It is like telling kids, "If you do this you will hurt yourself" YMMV but it won't :)
I wonder if it should be called "Law of Leaky Metaphors" instead. Metaphor is not the same thing as Abstraction. I can understand a "leaky metaphor" as something that does not quite make it, at least not in all aspects. But what would be a good EXAMPLE of a Leaky Abstraction?
The UX pyramid but applied to DX.
It basically states that you should not focus in making something significant enjoyable or convenient if you don't have something that is usable, reliable or remotely functional.
ha, someone needs to email Netlify...
Because rewriting old complex code is way more time consuming that you think it'll be. You have to add not only in the same features, but all the corner cases that your system ran into in the past.
Have seen this myself. A large team spent an entire year of wasted effort on a clean rewrite of an key system (shopping cart at a high-volume website) that never worked... ...although, in the age of AI, wonder if a rewrite would be easier than in the past. Still, guessing even then, it'd be better if the AI refactored it first as a basis for reworking the code, as opposed to the AI doing a clean rewrite of code from the start.
As you probably know, there is a tendency when new developers join a team to hate the old legacy code - one of the toughest skills is being able to read someone else's code - so they ask their managers to throw it away and rewrite it. This is rarely worth it and often results in a lot of time being spent recreating fixes for old bugs and corner cases. Much better use of time to try refactoring the existing code first.
Although, can see why you mentioned it from the initial example that I gave (on that rewrite of the shopping cart) which is also covered by the "second system effect." Yeah, thinking back, have seen this too. Overdesign can get really out of hand and becomes really annoying to wade through all that unnecessary complexity whenever you need to make a change.
https://web.archive.org/web/20260421113202/https://lawsofsof...
> When describing phenomena in the social world
> Software Engineers gravitate towards eponymous 'laws'.
It’s not a great list. The good old c2.com has many more, better ones.
> The first 90% of the code accounts for the first 90% of development time; the remaining 10% accounts for the other 90%.
It should be 90% code - 10% time / 10% code - 90% time
Most of them are also wrong
This one belongs to history books, not to the list of contemporary best practices.
YAGNI and "you will ship the org chart" are the two most commonly useful things to remember, but they aren't laws.
> Premature Optimization (Knuth's Optimization Principle)
> Another example is prematurely choosing a complex data structure for theoretical efficiency (say, a custom tree for log(N) lookups) when the simpler approach (like a linear search) would have been acceptable for the data sizes involved.
This example is the exact example I'd choose where people wrongly and almost obstinately apply the "premature optimization" principles.
I'm not saying that you should write a custom hash table whenever you need to search. However, I am saying that there's a 99% chance your language has an inbuilt and standard datastructure in it's standard library for doing hash table lookups.
The code to use that datastructure vs using an array is nearly identical and not the least bit hard to read or understand.
And the reason you should just do the optimization is because when I've had to fix performance problems, it's almost always been because people put in nested linear searches turning what could have been O(n) into O(n^3).
But further, when Knuth was talking about actual premature optimization, he was not talking about algorithmic complexity. In fact, that would have been exactly the sort of thing he wrapped into "good design".
When knuth wrote about not doing premature optimizations, he was living in an era where compilers were incredibly dumb. A premature optimization would be, for example, hand unrolling a loop to avoid a branch instruction. Or hand inlining functions to avoid method call overhead. That does make code more nasty and harder to deal with. That is to say, the specific optimizations knuth was talking about are the optimizations compilers today do by default.
I really hate that people have taken this to mean "Never consider algorithmic complexity". It's a big reason so much software is so slow and kludgy.
To be fair, a linear search through an array is, most of the time, faster than a hash table for sufficiently small data sizes.
It doesn't take long for hash or tree lookups to start outperforming linear search and, for small datasets, it's not frequently the case that the search itself is a performance bottleneck.
> The less you know about something, the more confident you tend to be.
From the first line on the wiki article:
> systematic tendency of people with low ability in a specific area to give overly positive assessments of this ability.
Or, said another way, the more you know about something the more complexities you're aware of and the better assessment you can make about topics involving such. At least, that's how I understand it in a nutshell without explaining the experiments run and the observations that led to the findings.
Also they used the graph for the Gartner Hype Cycle as the icon, not the Dunning-Kruger graph.
Just because some things were observed frequently during a certain period, doesn't mean it's a "Law" or even a "Principle"; it's merely a trend.
Here's another law: the law of Vibe Engineering. Whatever you feel like, as long as you vibe with it, is software engineering.
- NIH
- GIGO
- Rule of 3
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In most places, people don't follow this rule, as it ensures either you're working an extra 10-20 hours a week to keep things clean, or stuck at mid-level for not making enough impact.
I choose the second option. But I see people who utterly trash the codebase get ahead.
"Before SpaceX, launching rockets was costly because industry practice used expensive materials and discarded rockets after one use. Elon Musk applied first-principles thinking: What is a rocket made of? Mainly aluminum, titanium, copper, and carbon fiber. Raw material costs were a fraction of finished rocket prices. From that insight, SpaceX decided to build rockets from scratch and make them reusable."
Everything including humans are made of cheap materials but that doesn't convey the value. The AI got close to the answer with it's first sentence (re-usability) but it clearly missed the mark.
Law 0: Fix infra.
If you are saying you _can_ fix 90-99% of performance bottlenecks eventually with caching, that may be true, but doesn't sound as nice
Posterior probability of a prompt-created website: 99%.