In large projects, where hundreds of source files have to be compiled on every build, the long compilation time can be reduced significantly if templates are explicitly instantiated all at once. This is because when the compiler has to instantiate a template, its thread of execution is interrupted by the need to generate the code for that template specialization (template for a specific type), and only then can it resume parsing. When hundreds of sporadic templates are to be instantiated, it can make a difference. Therefore, it’s best to instantiate all templates in one source file explicitly, freeing the compiler from repeated interruption of its processing. Explicit request for template instantiation – as opposed to template definition – is characterized by the template keyword not followed by < as in the following examples:
template int min<int> (int, int); //function template instantiationtemplate class vector<string> //class template explicit instantiation
