Python 3000 idea: reversing the order of chained assignments

[Steve Holden]

Terry Reedy wrote:
> "Mark T" <nospam at nospam.com> wrote in message 
> news:DvGdnQacTuMlmp_bnZ2dnUVZ_uWdnZ2d at comcast.com...
> | This is interesting:
> |
> | >>> class Test(object):
> | ...   def __getattribute__(self,n):
> | ...     print 'reading',n
> | ...     return object.__getattribute__(self,n)
> | ...   def __setattr__(self,n,v):
> | ...     print 'writing',n,v
> | ...     return object.__setattr__(self,n,v)
> | ...
> | >>> x=Test()
> | >>> x.a=1; x.b=2; x.c=3
> | writing a 1
> | writing b 2
> | writing c 3
> | >>> x.a=x.b=x.c
> | reading c
> | writing a 3
> | writing b 3
> | >>>
> |
> | I wouldn't have expected "a" to be assigned first in a right-to-left 
> parsing
> | order.  The result is the same in any case.
> 
> The assignment order is specified in the language reference.

Where? I'm looking at

   http://docs.python.org/ref/assignment.html

right now.

> But many never read and those who do can forget.
> And even if the coder reads and remembers, a code reader may not have.
> Which is why I suggested multiple statements in explicit order when it 
> really matters.
> 
The current docs define

a, b = c, d

and

a = b, c, d

and

a, b, c = d

as valid assignments, but I can't find the part where

a = b = c

is defined. Help me out here. It looks as though the real syntax should 
be something like

assignment_stmt  	::=  	(target_list "=")+ expression_list |
                                 (target_list "=")+ assignment_stmt

regards
  Steve
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