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An interesting difference between classic and new style objects

Oren Tirosh oren-py-l at hishome.net
Mon Jan 7 08:09:46 EST 2002 
On Mon, Jan 07, 2002 at 10:30:13AM +0100, Alex Martelli wrote:
> However, PEP 252 also specifies:
> """
>     The introspection API is a read-only API.  We don't define the
>     effect of assignment to any of the special attributes (__dict__,
>     __class__ and __bases__), nor the effect of assignment to the
>     items of a __dict__.  Generally, such assignments should be
>     considered off-limits.  A future PEP may define some semantics for
>     some such assignments.
> """
> 
> As here we are indeed dealing with "assignment to [an item] of
> a __dict__", we may be in the grey zone to "be considered
> off-limits".  Some clarification would surely be welcome.

In this case __repr__ is not a special attribute.  It is a user attribute
with a well-known name that some builtin functions refer to.  There are even 
examples of this happening for attributes without underscores. 

There is no use of the introspection API, either.  I believe that assignment 
of attributes is well within the bounds of the basic language definition and
yet it produces different results for classic and new style objects.

	Oren
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