"template<>" vs "template" without brackets - what's the difference?
Suppose I've declared:
template <typename T> void foo(T& t);
Now, what is the difference between
template <> void foo<int>(int& t);
and
template void foo<int>(int& t);
semantically? And do template-with-no-brackets and template-with-empty-brackets have other semantics in other contexts?
Related to: How do I force a particular instance of a C++ template to instantiate?
Solution 1:
template <> void foo<int>(int& t);
declares a specialization of the template, with potentially different body.
template void foo<int>(int& t);
causes an explicit instantiation of the template, but doesn't introduce a specialization. It just forces the instantiation of the template for a specific type.
Solution 2:
With class/struct,
template <typename T> struct foo {};
Following is a specialization:
template <> struct foo<int>{};
Following is an explicit instantiation:
template struct foo<int>;