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From Marvin Humphrey <>
Subject Re: Native callbacks
Date Sun, 08 Jun 2008 06:02:16 GMT

On Apr 30, 2008, at 10:58 PM, Marvin Humphrey wrote:

> There's one significant problem left that I'm aware of: Perl's SUPER  
> mechanism is broken with the vtable override.

> The solution, I believe, is to have the XS bindings not invoke via  
> the vtable, but instead invoke the implementing function directly.   
> Unfortunately, that means a lot more binding code, because each  
> override requires its own binding.

I finally got around to implementing this, and it turns out to have  
been surprisingly easy.  The commit diff was only 137 lines long.

The size of the autogenerated binding file, KinoSearch.xs, went from  
13442 to 18401 lines.  On my Core 2 Duo MacBook Pro, compile time  
increased from about 15 to 20 seconds for that file, and from about 55  
to 60 seconds for all of KS.  That's perfectly acceptable, and a  
smaller increase than I'd expected.

The behavior of vtable methods is now virtually indistinguishable from  
that of native Perl methods from the point of view of the library  
user.  The only difference is that because the vtable pointers for  
subclasses are set when the DynamicVirtualTable object is created (the  
first time it is needed by a new object), dynamically generated  
methods created after that time won't trigger an override.  That's an  
esoteric use case, and I don't think it's even worth mentioning in the  

Marvin Humphrey
Rectangular Research

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