functor parameter problem

[Mitsukai]

hi i have a problem.

error: no matching function for call to `test1(int&, int)'

namespace test0 {

	template<typename test10, typename test11>
	const bool test1(bool&, const test10&, const test11&)
	{
		return(true);
	}
}

		template<typename test10, typename test11, typename test12>
		const bool test1(test10&, const test11&, const test12& = test0::test1)
		{
            return(false);
		}

int main(void)
{
    int x = 0;
    test1(x, 0);
}

i dont know why functor wrong.

[Mitsukai]

do anyonje know its kind of urgent

[Paul McKenzie]

Your test1 template takes three concrete (non-default) arguments. You are instantiating the template using only two arguments.

template<typename test10, typename test11, typename test12>
bool test1(test10&, const test11&, const test12& = test0::test1)
{
}

int main(void)
{
    int x = 0;
    test1(x, 0, true);  // this works
}

This compiles fine with Comeau.

Regards,

[spoulson]

What is the third parameter intended to be used for?

[SuperKoko]

Yep, template argument deduction on the second test1 overload can't be complete as test12 can't be deduced.

[Mitsukai]

i would rather hear a solution.

i have tried this:

    struct
    {
        template<typename test10, typename test11>
        const bool operator()(bool& x, const test10& y , const test11& z) const
        {
            return(x = true);
        }
    } test1;

		template<typename test10, typename test11, typename test12>
		const bool test2(test10& x, const test11& y, const test12& z = test1)
		{
		    bool a;
		    z(a, x, y);
            return(a);
		}

int main(void)
{
    int x = 0;
    test2(x, 0, test1);
}

it should be able to deduce test12 now but still no match.

[Paul McKenzie]

i would rather hear a solution.

So what do you call what I posted using your original code? There were no compilation errors in the example I posted if you specify the last parameter when the template is instantiated.

Now you've changed the code to a totally different example that doesn't compile for an entirely different set of reasons:

Thank you for testing your code with Comeau C/C++!
Tell others about http://www.comeaucomputing.com/tryitout !

Your Comeau C/C++ test results are as follows:

Comeau C/C++ 4.3.8 (Aug 19 2006 13:36:48) for ONLINE_EVALUATION_Alpha1
Copyright 1988-2006 Comeau Computing. All rights reserved.
MODE:strict errors C++

"ComeauTest.c", line 4: warning: type qualifier on return type is meaningless
const bool operator()(bool& x, const test10& y , const test11& z) const
^

"ComeauTest.c", line 8: error: use of a type with no linkage to declare a variable
with linkage
} test1;
^

"ComeauTest.c", line 11: warning: type qualifier on return type is meaningless
const bool test2(test10& x, const test11& y, const test12& z = test1)
^

"ComeauTest.c", line 21: error: a template argument may not reference an unnamed
type
test2(x, 0, test1);
^

2 errors detected in the compilation of "ComeauTest.c".

In strict mode, with -tused, Compile failed

struct test1
{
     template<typename test10, typename test11>
     bool operator()(bool& x, const test10& y , const test11& z) const
     {
          return(x = true);
     }
};

test1 test_inst;

template<typename test10, typename test11, typename test12>
bool test2(test10& x, const test11& y, const test12& z = test_inst)
{
   bool a;
   z(a, x, y);
   return(a);
}

int main(void)
{
    int x = 0;
    test2(x, 0, test_inst);
}

This compiles fine.

Regards,

Paul McKenzie

[Mitsukai]

but this does not .

    struct test1t
    {
        template<typename test10, typename test11>
        const bool operator()(bool& x, const test10& y , const test11& z) const
        {
            return(x = true);
        }
    };

    test1t test1;

		template<typename test10, typename test11, typename test12>
		const bool test2(test10& x, const test11& y, const test12& z = test1)
		{
		    bool a;
		    z(a, x, y);
            return(a);
		}

int main(void)
{
    int x = 0;
    test2(x, 0);
}

[Paul McKenzie]

It doesn't compile for the same reasons as the first example.

Regards,

Paul McKenzie