[fpc-devel] understanding generics

Paul Ishenin webpirat at mail.ru
Fri Nov 13 16:08:21 CET 2009


Hello, FPC developers' list

I am trying to understand how to add an enumerator support to the fgl 
containers. Seems it is imposible.

I need enumerator to return the same type as generic container. So I 
declared enumerator class as generic too. But how to use it inside the 
generic container class?

I guessed to use the next construction:

generic  TFPGList<T>   =  class(TFPSList)
type  public
   TFPGListEnumeratorSpec   =  specialize  TFPGListEnumerator<T>;
....

Everything compiles fine, but when I declare a specialize type for the 
generic  TFPGList I get very strange compiler errors.

I attached a simple project which exposes the bug.

My fgl patch which I tried to make work is here: 
http://www.hu.freepascal.org/fpcircbot/cgipastebin?msgid=18801

Best regards,
Paul Ishenin.
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