CODEWITHSUNDEEP
c++
user3365609
user3365609

Reputation:

Where to place helper function for 2 files?

I have 4 files: f.h,f.cpp,g.h,g.cpp. both f.h and f.cpp include g.h, but f.cpp and g.cpp have a common helper function (Note f.h doesn't need it, but it needs definitions that are in g). At the moment I have the helper function as free standing in g.h (so that both g.cpp and f.cpp include it). However, this scares me because: 1.Whoever includes f.h can use it freely (meaning encapsulation) 2.If he has a function that has the same name as the free function it won't compile

I'm really hoping for a solution without code duplication (it's not a big helper functions, just a few lines. It's the principle :P).

Upvotes: 1

Views: 906

Answers (3)

kmdreko
kmdreko

Reputation: 60051

You have a few options

What you describe (only a few .cpps need it and no one else should use it) sounds like what'd I'd call an "internal" function.

  • Make a new .h file for this function and others like it called internal.h or detail.h or impl.h or something sensical.

  • Put the function in f.h (or even a new file like above) and use a namespace to section off code that should not be used by normal users. 

    namespace internal { // or "detail" or whatever
    // function here
}

    This is what many people and open source projects do.

  • If you really really don't want anything else to use this function, you can stick it as a private static member of a class and make friend only your classes. 

    class PrivateFunctions {
private:
    // static your function
    // friend your classes
};

    I'd advise against this method though because it's uncommon, hard to change, and verbose

Upvotes: 1

holzkohlengrill
holzkohlengrill

Reputation: 1222

If you need more access control you can make it a friend function.

Another option is to create a new file for the helper function and include it where needed. For only one function I wouldn't do that. Depends on you future plans.

Upvotes: 0

R Sahu
R Sahu

Reputation: 206577

Create g_f_private.h. Add all the helper classes/functions/declarations in it that are used only by f.cpp and g.cpp.

#nclude it in f.cpp and g.cpp.

Don't expose it to the users of f.h and g.h.

Upvotes: 2

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