strange template error

[reinisr]

Hi!

This program:

template<class T_index, class T_data>
class AAA
{
public:
AAA(int ii = 0,int jj = 0) {}
};

AAA<int, int> a1(10, 20); // this works
AAA<int, int> a3(10, 20); // this works

class BBB
{
AAA<int, int> a4; // this works
AAA<int, int> a5(10, 20); // this doesn't work
};

int main()
{
return 0;
}

fails to compile, I tried
g++296 and g++32 give errors:
test.cpp:17: invalid data member initiailization
test.cpp:17: use `=' to initialize static data members

g++34 g++4 give errors:
test.cpp:17: error: expected identifier before numeric constant
test.cpp:17: error: expected `,' or `...' before numeric constant
test.cpp:17: error: ISO C++ forbids declaration of `parameter' with no
type

I tried to play with typename keyword with no success.
I wonder what Bjarne Stroustrup is going to say about this mess.

Any ideas?

Reinis

 

[dragoncoder]

Hi!

This program:

template<class T_index, class T_data>
class AAA
{
public:
AAA(int ii = 0,int jj = 0) {}
};

AAA<int, int> a1(10, 20); // this works
AAA<int, int> a3(10, 20); // this works

class BBB
{
AAA<int, int> a4; // this works

This is a declaration.

AAA<int, int> a5(10, 20); // this doesn't work

Here you are trying to define (initialize) a member object, you are not
supposed to do that inside the class body. You need to do this inside
BBB constructor.

 

[red floyd]

This is a declaration.


Here you are trying to define (initialize) a member object, you are not
supposed to do that inside the class body. You need to do this inside
BBB constructor.

To be more precise, the compiler-generated default constructor for BBB
default constructs a4. a5 is a syntax error.

To do what you want:

class BBB
{
AAA<int, int> a4;
AAA<int, int> a5;
public:
BBB() : a4(), a5(10, 20) { }
};