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[Python-Dev] Python memory model (low level)

Nick Maclaren nmm1 at cus.cam.ac.uk
Fri Jun 30 20:44:22 CEST 2006 
I Have been thinking about software floating point, and there are
some aspects of Python and decimal that puzzle me.  Basically, they
are things that are wanted for this sort of thing and seem to be
done in very contorted ways, so I may have missed something.

Firstly, can Python C code assume no COMPACTING garbage collector,
or should it allow for things shifting under its feet?

Secondly, is there any documentation on the constraints and necessary
ritual when allocating chunks of raw data and/or types of variable
size?  Decimal avoids the latter.

Thirdly, I can't find an efficient way for object-mangling code to
access class data and/or have some raw data attached to a class (as
distinct from an instance).

Fourthly, can I assume that no instance of a class will remain active
AFTER the class disappears?  This would mean that it could use a
pointer to class-level raw data.

I can explain why all of those are the 'right' way to approach the
problem, at an abstract level, but it is quite possible that Python
does not support the abstract model of class implementation that I
am thinking of.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:  nmm1 at cam.ac.uk
Tel.:  +44 1223 334761    Fax:  +44 1223 334679
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