Re: [Boost-users] boost & c-style calback issue

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Michael Bradley Jr wrote:

Hi,

i'm facing this problem may be someone on the list do have an elegant solution

This is really not a boost-related problem; this is basic C++.

class A; class B;

class C { int operator () (A*,B*) };

Try making class C look more like this: class C { int operator()(); A aInstance; B bInstance; }; You can then modify the operator() function to use aInstance and bInstance instead of using parameters to pass them in.

typedef int (*foobar)(A*,B*); void do_something(foobar cb);

Just a suggestion - eliminate all typedef statements from your code until you really understand what your code is doing. Typedefs are merely aliases that will add to your confusion.

C obj; do_something(obj); *ERROR*

Yes, this is an error: - 'obj' is an instance of C that knows absolutely nothing about A or B - 'do_something()' is a function that expects a function pointer (with pointer-to-A and pointer-to-B as its parameters) and knows nothing about C

did try boost::function ftor = obj; do_something(ftor); *ERROR*

compiler generates in both cases the following error messages cannot convert parameter 2 from 'boost::function<Signature>' to 'int (__cdecl *)(A *,B *)'

with 1> [ 1> Signature=int (A *, B *) 1> ] 1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

I can't make the corresponding class B member function static due to side-effects.

There is no class B member function mentioned anywhere in your sample...

Any clue how to get rid of this?

Thanks in advance Mike

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