Template constructor in a class template - how to explicitly specify template argument for the 2nd parameter?

Question

Template constructor in a class template - how to explicitly specify template argument for the 2nd parameter?

compile error when tried to explicit specify template

Answer 1

Fixing your code, the following would work:

template class TestTemplate {
public:
    //constructor 1
    template TestTemplate(Y * p) {
        cout << "c1" << endl;
    }

    //constructor 2
    template TestTemplate(Y * p, D d) {
        cout << "c2" << endl;
    }

    template
    void foo(A a, B b) {
        cout << "foo" << endl;
    }
};

int main() {
    TestTemplate tp(new int());

    tp.foo(new int(), "hello");

    TestTemplate tp2(new int(),2);
}

You cannot use T for the class template parameter and the constructor template parameter. But, to answer your question, from [14.5.2p5]:

Because the explicit template argument list follows the function template name, and because conversion member function templates and constructor member function templates are called without using a function name, there is no way to provide an explicit template argument list for these function templates.

Therefore, you cannot explicitly specify template arguments for constructor.