For review: PEP 343: Anonymous Block Redux and Generator Enhancements

Steven Bethard steven.bethard at gmail.com
Mon Jun 6 01:30:12 CEST 2005


Nicolas Fleury wrote:
> Since the current syntax would be there, the no-indentation syntax can 
> be explained in terms of the indentation syntax:
> 
> """
> To avoid over-indentation, a with-statement can avoid defining a new 
> indentation block.  In that case, the end of the with block is the end 
> of the current indentation block.
> 
> with EXPR as VAR
> REST OF BLOCK
> 
> is equivalent to
> 
> with EXPR as VAR:
>     BLOCK
> """
> 
> What do you think?  I fail to see the complexity...

I guess my only real qualm about this is that I think it makes it harder 
to see where __exit__() methods are called.  When I compare:

def func(arg, baz):
     foo = bar(arg)
     with x as foo(baz)
     x.frobble()
     with y as x.bop()
     return frabble(x, y)

with:

def func(arg, baz):
     foo = bar(arg)
     with x as foo(baz):
         x.frobble()
         with y as x.bop():
             return frabble(x, y)

I find it much easier to identify in the second one that __exit__() 
methods will be called right before the function returns (after the 
return statement).  YMMV.

BTW, if you really like the optional-indentation idea, you should post 
it to the Wiki page (http://wiki.python.org/moin/WithStatement) -- 
Guido's been pretty quick to respond to any comments made there, so you 
could get some feedback much more useful than I can give you. ;)

STeVe



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