C++ Inline functions and template function in header-only library

Question

In order to avoid code bload due to over-inlining...
Is this a valid way to implement a template function that acts like an inline function?

Original inline function declaration:

inline double MyInlineFunction(){
        return 3.141592653589;
}

Alternative function declaration using template function:

template<typename T = void> double MyInlineFunctionT(){
    return 3.141592653589;
}

I hope you're not using `inline` to "help" the compiler optimize your code but you're doing it for linker purposes. — Hatted Rooster, Apr 26 '17 at 17:40
This seems like a waste of time with any modern compiler. Modern compilers will make their own decisions regarding `inline` (perhaps using the keyword as a hint) on a case-by-case basis. Additionally, modern compilers can usually eliminate unused code. — François Andrieux, Apr 26 '17 at 17:40
Just for linking propouse, in order to avoid to distribute and compile another cpp source file whit the function implementation. — ar-org-austral, Apr 26 '17 at 17:54

score 3 · Answer 1 · answered Apr 26 '17 at 18:21

Marking a function inline tells the compiler that it's okay to have the same function defined in more than one translation unit. It's also a hint that the function ought to be expanded inline, but most compilers make their own judgment in that regard. Similarly, a template function can be instantiated in more than one translation unit, and compilers will make their own judgment as to whether to expand it inline.

Short version: there's no difference in code size. But the template version is harder to understand, harder to compile, harder to use, and more likely to produce errors.

C++ Inline functions and template function in header-only library

1 Answers1