Question

I have two libraries (third-party), and within each of these libs they have defined two classes with same name (in header files).

// Lib A, HeaderA.h
struct mycompare
{
//Some code
};

// Lib B, HeaderB.h
struct mycompare
{
//Same code
};

Please note that, in both libs, mycompare name and the implementation is same. How to use both header files same time ?

Answer 1

Assuming you can’t edit the headers/libraries:

• indirection: create your own out-of-line wrapper for the simpler of A and B, which includes HeaderA.h or HeaderB.h only in the implementation.
  • this is similar to but much less work and coupling than Als’s option 2 😉
• shameless hackery: include HeaderA.h, then #define mycompare mycompare_duplicate before including HeaderB.h, then #undef mycompare. This could bite you if one of the implementations later changes, and may not be possible if the header later uses the symbol itself (e.g. as a function argument, where type name-mangling would differ and prevent your calls being resolved).

If you can edit the libraries, then obviously the best long-term option is to put their functionality into separate namespaces.