From: Rupert Bruce (rupert_at_[hidden])
Date: 2008-06-02 10:41:37
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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<int(A*,B*)> 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
>
>
>
>
>
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://listarchives.boost.org/mailman/listinfo.cgi/boost-users
>
>
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