From: nobu.nokada@...
Date: 2002-07-26T09:56:48+09:00
Subject: Re: A couple of questions on writing extensions

Hi,

At Fri, 26 Jul 2002 06:09:35 +0900,
Matthew Bloch wrote:
> *) what does 'Died with exception wrong argument type Object (expected Data)' 
> mean?

Literally, you passed something else to the method expecting
Data.

> which is nothing to do with my converted class, but the error implies 'key' is 
> somehow corrupt or of the wrong type, where the same code worked before.  
> This exception seems to be thrown from different points depending on timing 
> (though more often than not in a simple call to a logger), which is pretty 
> difficult to track down.

I vote GC issue.  How do you define mark/free functions for
Data_{Make,Wrap}_Struct?  Could you show us the source?

> *) Is this kind of construct safe as the end of a bog-standard native accessor 
> method? :

Yes.

> i.e. constructing a temporary object with the same value as the one inquired 
> about?  Might it be garbage collected before being read by the Ruby caller?  
> Will it be garbage-collected when the result goes out of context in the 
> calling Ruby method?

While it is referred by `self', never collected.

> *) is this a correct way to call back a method implemented in class derived 
> from a C extension class? :

Yes.