Re: Need help with dynamic_cast across shared libraries with gcc 3.2.3.

["Yuly Novikov" <novikov_yuly at hotmail dot com>]

Unfortunately in the real code I use multiple inheritance + virtual 
inheritance, so reinterpret_cast will return wrong pointer.
Any other ideas?


> From: Eljay Love-Jensen <eljay@adobe.com>
> To: "Yuly Novikov" <novikov_yuly@hotmail.com>, gcc@gcc.gnu.org,   
> gcc-help@gcc.gnu.org
> CC: novikov_yuly@hotmail.com
> Subject: Re: Need help with dynamic_cast across shared libraries with  gcc 
> 3.2.3.
> Date: Thu, 17 Jul 2003 09:43:21 -0500
>
> Hi Yuly,
>
> >Is there any other way to make the algorithm above work with gcc 3.2.3?
>
> If you KNOW the pointer is the given type, use a 
> reinterpret_cast<foo*>(ptr) instead of a dynamic_cast<foo*>(ptr).  And put 
> a BIG disclaimer in your source code saying "This is correct.  All your 
> {derived class pointer name} are belong to us."
>
> Also note:  if you use those kinds of objects for exceptions in your 
> across-shared-library boundaries, you'll probably run into situations where 
> your code fails to catch the object.  The dynamic_cast mechanism uses the 
> same RTTI information that the exception handling's catch mechanism uses.   
> And, similiarly, you'll probably experience problems using the RTTI 
> mechanism if you use typeid and type_info.
>
> HTH,
> --Eljay
>
> PS: you shouldn't need to dynamic_cast the derived pointer to the base 
> pointer type.  A derived pointer IS-A base pointer, already.

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