Default template arguments in function templates

[George Sakkis]

Hi all,

I have the following two template function definitions:

template <typename Container, typename Sepatator>
string join(const Container& c, const Sepatator& s) {
// ...
}

template <typename Container>
string join(const Container& c) {
return join(c, ' ');
}

I tried to merge them into one using a default argument for Separator, but the compiler (gcc 3.3.1)
complains that default template arguments may not be used in function templates. What's the reason
for this limitation and, more importantly, is there a workaround for it ?

TIA,
George

 

[Victor Bazarov]

I have the following two template function definitions:

template <typename Container, typename Sepatator>
string join(const Container& c, const Sepatator& s) {
// ...
}

template <typename Container>
string join(const Container& c) {
return join(c, ' ');
}

I tried to merge them into one using a default argument for Separator, but the compiler (gcc 3.3.1)
complains that default template arguments may not be used in function templates. What's the reason
for this limitation and, more importantly, is there a workaround for it ?

Ask in comp.std.c++ bout the reasoning behind prohibiting the default
template arguments for function templates, they discuss the actual
Standard document, they know the rationales for different parts of it
for sure. As to the work-around, you already have it: don't merge, keep
the two functions separate.

V