Ivo wrote:
>
> Suppose I have a class C and a function
>
> void f(const C&);
>
> Now, I want to provide a default argument for this function,
> something like
>
> void f(const C& c=C());
>
> (provided that class C defines a meaningful public default constructor).
>
> Unfortunately, this construct is not aligned with the latest C++ standard.
> Indeed, MSVC++ (debug mode only) would report a warning, while GNU C++
> compilers would report an error.

I don't understand your problem.
The program below compiles with no warnings and runs with
gcc version 2.95.2 19991024 (release)

#include <iostream>

class C {
public:
  C() {}
};

void f( const C& c=C());

void f( const C& c)
{
}

int main( int argc, char** argv)
{
  C c;
  f(c);
  f();
  cout << "Done.\n";
  return 0;
}

Dennis Yelle

--
I am a computer programmer and I am looking for a job.
There is a link to my resume here:  http://table.jps.net/~vert

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Suppose I have a class C and a function

void f(const C&);

Now, I want to provide a default argument for this function,
something like

void f(const C& c=C());

(provided that class C defines a meaningful public default constructor).

Unfortunately, this construct is not aligned with the latest C++ standard.
Indeed, MSVC++ (debug mode only) would report a warning, while GNU C++
compilers would report an error.

To apply a fixture, I can declare something like

void f(const C& c=(C&)(const C&)C());

Otherwise, I can overload my function f

void f(const C&);
void f() {C c; f(c);};

In the case I need it frequently, for different classes and their various
constructors (with or without parameters), I can (reluctantly) use a
macro definition:

TEMP_OBJ_INST(T) (T&)(const T&)T
void f(const C& c=TEMP_OBJ_INST(C)());
void g(const D& d=TEMP_OBJ_INST(D)(-1, 3.14));

- where D was another class with public constructor D(int, double).

Is there any other, more elegant way to put it right?

Thanks,
Ivo


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