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Comment by throwawayaway | Hacker News Reader

The problem with non member functions is that, once you start preferring them, you are basically writing C. They are contagious. There's very little reason for class members unless you want inheritance or polymorphism. Scott Meyers has also promoted them:

http://www.drdobbs.com/cpp/how-non-member-functions-improve-...

With non member functions declared in the header and defined in a .C file, and suddenly you don't have RIAA any more or exceptions. Your .C files end up being your division of concerns, not classes.

The only time you end up using any C++ features is interacting with a library that prefers member functions.

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Well, the key thing is the `reason` here. In C++ we use RAII, so this is the reason to have a member constructor/destructor functions instead of non-member create_something(...)/destroy_something(...) (aka C style).

But, for instance, `sort` is a good candidate to have outside of a class - and it actually is a global function - std::sort.

RAII is your reason.

When you start preferring non member functions, you tend allocate on the stack.

There are rare items that require heap allocation and other resources. For those you can have classes. What I am saying is that when you prefer non member functions you end up with very few classes.

You don't use classes only to get RAII. They are also useful when you have data with invariants, which the constructor establishes. And of course, if you want to use private data.

by invariants do you mean constant values?

there's many ways to implement private data. if you prefer non member functions, a class is a bunch of extra keystrokes to achieve the same as the old fashioned C private data.

if you prefer non member functions to member functions, your private data becomes a global variable or struct in a file, and the private data is not accessible by getter/setter functions that are externalised.

Having access to private data (implementation details) is another reason to have a member function.

Unless you're a fan of `friend` keyword ;)

i think you need to read my comment again because "private:" in a class is not the only way to implement private data. you are only repeating what the parent commenter said.

Well, to follow your line - virtual functions can also be implemented with some function pointer stuff within C. We're not discussing implementing various C++ stuff in C, we're talking about C++ itself.

be that as it may, it requires more keystrokes to implement virtual functions in C than it does in C++.

however, it requires less keystrokes to implement private data in C, than it does to create a class to store private data.

therefore it's questionable, if you are preferring non member non friend functions, whether you should use classes when you want private data.

i refute the idea that private data is a reason to use classes, if you are preferring non member non friend functions as advocated by Stroustrup, Meyers and Stepanov.

as i said already

> There's very little reason for class members unless you want inheritance or polymorphism.

This idea that 'files' are an organizing principle is bankrupt. In an editor I don't even know what file a method is in. Including header files is an annoyance, and should be automated.

In fact all code should be in a database, not a file, so changes can be tracked and attributed properly. So a tool can distinguish between 'lines being edited' and 'one function deleted and another added'. And so on.

So what organizing principle is left, since files are largely invisible during the coding process? Well, classes spring to mind.

I think you need a better editor if you don't know what file a method is in.

There will be very few classes in your project if you decide to prefer non member non friend functions as suggested here.

The question being, whether you go along with that suggestion or not?

I guess that wasn't clear. I surf methods, not by opening files, but by going directly to the definition or declaration as needed. Sure its in some file, but I deal with 1000 methods and sure don't make any effort to memorize where they are - since its entirely irrelevant to the correctness of the code.

To make it clear: I favor factoring APIs into classes.

I think factoring api's into classes makes a lot of sense too, I think this idea of preferring non member functions undoes a lot of the functionality and team building cohesiveness that C++ offers.

It's strange that C++ luminaries like Stepanov, Meyers and Stroustrup favour non member functions.

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