Does it matter if there are unused functions I put into a big CoolFunctions.h / CoolFunctions.m file that's included everywhere in my project?

Question

I want to create a big file for all cool functions I find somehow reusable and useful, and put them all into that single file. Well, for the beginning I don't have many, so it's not worth thinking much about making several files, I guess. I would use pragma marks to separate them visually.

But the question: Would those unused methods bother in any way? Would my application explode or have less performance? Or is the compiler / linker clever enough to know that function A and B are not needed, and thus does not copy their "code" into my resulting app?

Answer 1

I don't think having unused functions in the .h file will hurt you in any way. If you compile all the corresponding .m files containing the unused functions in your build target, then you will end up making a bigger executable than is required. Same goes for if you include the code via static libraries.

If you do use a function but you didn't include the right .m file or library, then you'll get a link error.

Answer 2

The code would still be compiled and linked into the project, it just wouldn't be used by your code, meaning your resultant executable will be larger.

I'd probably split the functions into seperate files, depending on the common areas they are to address, so I'd have a library of image functions separate from a library of string manipulation functions, then include whichever are pertinent to the project in hand.

Answer 3

This sounds like an absolute architectural and maintenance nightmare. As a matter of practice, you should never make a huge blob file with a random set of methods you find useful. Add the methods to the appropriate classes or categories. See here for information on the blob anti-pattern, which is what you are doing here.

To directly answer your question: no, methods that are never called will not affect the performance of your app.

Answer 4

No, they won't directly affect your app. Keep in mind though, all that unused code is going to make your functions file harder to read and maintain. Plus, writing functions you're not actually using at the moment makes it easy to introduce bugs that aren't going to become apparent until much later on when you start using those functions, which can be very confusing because you've forgotten how they're written and will probably assume they're correct because you haven't touched them in so long.

Also, in an object oriented language like Objective-C global functions should really only be used for exceptional, very reusable cases. In most instances, you should be writing methods in classes instead. I might have one or two global functions in my apps, usually related to debugging, but typically nothing else.

So no, it's not going to hurt anything, but I'd still avoid it and focus on writing the code you need now, at this very moment.