C++ Question
Storing C++ template function definitions in a .CPP file
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.
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Answer Source
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.
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