Re: [Boost-users] Type List Iteration?

From: Sohail Somani (s.somani_at_[hidden])
Date: 2005-10-04 16:47:29

Is there some trouble with defining:

class Base
{
        virtual void some_function() = 0;
};

???

I can understand the void f() entry point for C callbacks but you can
use C++ to do the work for you. Unless I'm missing something.

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] 
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Duane Murphy
> Sent: Tuesday, October 04, 2005 2:38 PM
> To: Boost Users
> Subject: [Boost-users] Type List Iteration?
> 
> 
> How do I iterate over a type list and call a function? MPL?
> 
> I have a base class BASE that has several subclasses A, B, C 
> that have special capabilities, but no way to identify those 
> capabilities aside from the type.
> 
> I would like to determine if an object of type BASE is also 
> of one of the special subclasses:
> 
> ie
> void f( BASE* base)
> {
>     if ( dynamic_cast< A* >( base ) != NULL )
>     {
>         some_function( dynamic_cast< A* >( base ) );
>     }
>     else if ( dynamic_cast< B* >( base ) != NULL )
>     {
>         some_function( dynamic_cast< B* >( base ) );
>     }
>     else if ( dynamic_cast< C* >( base ) != NULL )
>     {
>         some_function( dynamic_cast< C* >( base ) );
>     }
> }
> 
> I think you can see why I'd like a type list iterator 
> solution to this. 
> 
> I have arranged for the some_function to be a template as 
> well to make things easier.
> 
> What I am looking for is the equivalent of find_if() but for 
> types and done at run time. I looked over MPL, but MPL seems 
> to apply at compile time without a door to the run time world. :-)
> 
> Thanks for your helpful tips!
> 
>  ...Duane
> 
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