Hello all,
At the line marked "Problem here???" below, I get successful compilation on
one platform and failure on another. What does the Standard say about this?
Is this a correct program? May a member function be called through a
pointer when some parameter default values are accepted (i.e. not all
parameters are passed)?
Thanks,
Dave
#include <iostream>
using namespace std;
class foo
{
public:
int do_it(int = 10) {return 42;}
};
template <typename RET, typename OBJECT_TYPE, typename PTR_TO_MEM_FUN>
RET call_it(OBJECT_ TYPE &ds, PTR_TO_MEM_FUN pm)
{
return (ds.*pm)(); // Problem here???
}
int main()
{
foo bar;
cout << call_it<int>(ba r, &foo::do_it) << endl;
} 2 1470
Dave <be***********@ yahoo.com> spoke thus: #include <iostream>
using namespace std;
class foo { public: int do_it(int = 10) {return 42;} };
template <typename RET, typename OBJECT_TYPE, typename PTR_TO_MEM_FUN> RET call_it(OBJECT_ TYPE &ds, PTR_TO_MEM_FUN pm) { return (ds.*pm)(); // Problem here???
^^^^ I don't think this is legal :)
}
int main() { foo bar;
cout << call_it<int>(ba r, &foo::do_it) << endl; }
(I'm not an authority; any of the below could be [really?] wrong!)
Well, among other things, you didn't complete the template
specification (I'm sure that's the wrong word...) - the template takes
three arguments, and you only supplied one. Another thing is that
template arguments should be object types, and a pointer to a member
function doesn't sound like it belongs there.
--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.
"Christophe r Benson-Manica" <at***@nospam.c yberspace.org> wrote in message
news:c6******** **@chessie.cirr .com... Dave <be***********@ yahoo.com> spoke thus:
#include <iostream>
using namespace std;
class foo { public: int do_it(int = 10) {return 42;} };
template <typename RET, typename OBJECT_TYPE, typename PTR_TO_MEM_FUN> RET call_it(OBJECT_ TYPE &ds, PTR_TO_MEM_FUN pm) { return (ds.*pm)(); // Problem here??? ^^^^ I don't think this is legal :)
}
int main() { foo bar;
cout << call_it<int>(ba r, &foo::do_it) << endl; }
(I'm not an authority; any of the below could be [really?] wrong!)
Well, among other things, you didn't complete the template specification (I'm sure that's the wrong word...) - the template takes three arguments, and you only supplied one. Another thing is that template arguments should be object types, and a pointer to a member function doesn't sound like it belongs there.
-- Christopher Benson-Manica | I *should* know what I'm talking about - if I ataru(at)cybers pace.org | don't, I need to know. Flames welcome.
The other two template parameters are deduced by the compiler.
A template type parameter does not have to be of class type. It may be of a
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