Storing C++ template function definitions in a .CPP file
c++, templates
Solution
The problem you describe can be solved by defining the template in the header, or via the approach you describe above.
I recommend reading the following points from the C++ FAQ Lite:
- Why can’t I separate the definition of my templates class from its declaration and put it inside a .cpp file?
- How can I avoid linker errors with my template functions?
- How does the C++ keyword export help with template linker errors?
They go into a lot of detail about these (and other) template issues.
Problem
I have some template code that I would prefer to have stored in a CPP file instead of inline in the header. I know this can be done as long as you know which template types will be used. For example: .h file ``` class foo { public: template <typename T> void do(const T& t); }; ``` .cpp file ``` template <typename T> void foo::do(const T& t) { // Do something with t } template void foo::do<int>(const int&); template void foo::do<std::string>(const std::string&); ``` Note the last two lines - the foo::do template function is only used with ints and std::strings, so those definitions mean the app will link. My question is - is this a nasty hack or will this work with other compilers/linkers? I am only using this code with VS2008 at the moment but will be wanting to port to other environments.