Re: Problem with function not being visible

From:

"Victor Bazarov" <v.Abazarov@comAcast.net>

Newsgroups:

comp.lang.c++

Date:

Tue, 24 Apr 2007 15:02:15 -0400

Message-ID:

<f0lk7p$7cl$1@news.datemas.de>

chris@foobar.com wrote:

Guys, I have the following piece of code. Could you please help me
understand why b.ToString( ) cannot be called while b.foo( ) can?
When I compile I get (gcc, but visual studio gives the same pretty
much). Thanks

Binding a reference to non-const to a temporary is prohibited.

$ g++ -Wall foo.cpp
foo.cpp: In function `int main(int, char**)':
foo.cpp:21: error: no matching function for call to `Bar::ToString()'
foo.cpp:14: note: candidates are: virtual std::string
Bar::ToString(std::string&) const

#include <stdlib.h>
#include <string>
using namespace std;

template <typename _T> class Foo {

You should avoid using names that begin with an underscore and
a capital letter. They are reserved by the implementation.

public:
virtual std::string ToString (std::string& pfx) const = 0;
std::string ToString ( ) const { return(ToString(std::string( ))); }

Are you trying to call the virtual function (declared just before) here?
You cannot bind the temporary to a refernece to non-const. You have to
change the body to be

{ std::string s; return ToString(s); }

virtual void* _foo ( ) const = 0;
void* foo( ) const { return (_foo( )); }
};

class Bar: public Foo<int> {
public:
std::string ToString (std::string& pfx) const
{ return (std::string("test")); }
void* _foo ( ) const { return(NULL); }

I've reformatted it a bit, just to fit them on a line.

};

int main (int argc, char **argv) {
Bar b;
b.foo( );
b.ToString( );
return (0);
}

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask