Template type deduction in C++ for Class vs Function?

Question

Why is that automatic type deduction is possible only for functions and not for Classes?

Answer 1

In specific cases you could always do like std::make_pair:

template
make_foo(T val) {
    return foo(val);
}

EDIT: I just found the following in "The C++ Programming Language, Third Edition", page 335. Bjarne says:

Note that class template arguments are never deduced. The reason is that the flexibility provided by several constructors for a class would make such deduction impossible in many cases and obscure in many more.

This is of course very subjective. There's been some discussion about this in comp.std.c++ and the consensus seems to be that there's no reason why it couldn't be supported. Whether it would be a good idea or not is another question...