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Comment by ghosty141 | Hacker News Reader

I personally love the idea of DoD but from my experience it rarely works well in practice since one of the key assumptions of understanding ur problem is often not given as new requirements pop up and change all the time.

At work we are rewriting and reengineering system from scratch and its crazy because the limitations of the old system are now gone we get the most insane feature requests that are even accepted by the team lead et al. This makes such an approach impossible since DoD is exactly the opposite of flexible design in my opinion.

Im curious has anybody really followed this in a big long living commercial project?

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DoD may be a good idea for a business context where one of your main priorities is getting the most efficient use out of memory bandwidth & cache.

E.g. if your job is writing game engines or middleware used by AAA games with fancy graphics to run on consumer hardware, getting the most efficient use out of the players' limited memory bandwidth may be very important.

For many (most?) arbitrary commercial software projects in other contexts, performance isn't high priority & memory bandwidth isn't a bottleneck. Performance just has to be 'good enough' & 'good enough' performance may be easily attained by writing typical OO code that uses cache & memory very inefficiently - so in those cases DoD is an engineering trade off that solves a problem that doesn't need to be solved & may create new problems if introduced.

I have business oriented C++ backend where I use mostly OOP but also use DoD in few critical places that do a lot of calculations over big chunks of data. It is simpler than for games since I only need high average performance, not real time 60 or whatever FPS with no jitter.

A mindset like this has led to my TV taking 40 seconds to boot and glitching/lagging just during simple navigation, even though its hardware is about 10,000x better than what got us to the moon.

Based on your description the only prescriptive thing one can say is lean into composition and avoid inheritance. While there are some pitfalls with composition it is easier to unpack and restructure than inheritance is. Changing requirements will of course incur changing data structures etc. but hopefully this can be avoided a bit by using LUT/indexes and other things to minimize impact.

Why do you lowercase "oriented" when "DOD" (and "OOD") is the usage in the slides?

Autocorrect to Department of Defense?

good question, autocorrect in a non english language.

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