[pypy-dev] Support for __getitem__ in rpython?

Simon Burton simon at arrowtheory.com
Fri Dec 5 07:15:36 CET 2008

On Thu, 4 Dec 2008 10:15:34 +0100
"Hakan Ardo" <hakan at debian.org> wrote:

> Hi,
> I've started to play around with the pypy codebase with the intention
> to make obj[i] act like obj.__getitem__(i) for rpython objects. 


> The
> approach I tried was to add:
>  class __extend__(pairtype(SomeInstance, SomeObject)):
>      def getitem((s_array, s_index)):
>          s=SomeString()
>          s.const="__getitem__"
>          p=s_array.getattr(s)
>          return p.simple_call(s_index)
> and then do something like:
>  class __extend__(pairtype(AbstractInstanceRepr, Repr)):
>      def rtype_getitem((r_array, r_key), hop):
>          hop2=hop.copy()
>          ...
>          hop2.forced_opname = 'getattr'
>          hop2.dispatch()
>          hop3=hop.copy()
>          ...
>          hop3.forced_opname = 'simple_call'
>          hop3.dispatch()


> But I am having a hard time understanding the rtyper and if this is
> the right approach?  Is there anything similar in the code/docs I
> could look at to get a better understanding on how to write this?

I had lots of fun last year writing code in rpython/numpy .
There is plenty of getitem goodness there. Unfortunately it
is probably impenetrable. Um. Perhaps you could revert back to
when the code was sane (but much less functional).

I also had a whack at __str__ for classes but failed horribly.

Keep pestering me and i'm likely to become interested in this stuff again.

Cheering from afar,


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