On Sun, Jan 22, 2012 at 1:36 PM, Chris Rebert <pyideas@rebertia.com> wrote:

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On Sun, Jan 22, 2012 at 4:04 AM, Paul Moore <p.f.moore@gmail.com> wrote:

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On 22 January 2012 04:51, Steven D'Aprano <steve@pearwood.info> wrote:

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Assignment as an expression feels unnatural to me:

if spam() as x != 'ham':    frobulate(x)

doesn't really correspond to any natural English order.

While in general I agree with you, there *is* a natural reading of this:

"if spam() isn't 'ham', frobulate it"

The fact that you have to choose a name is because computer languages have to be more explicit than natural languages, and can't deal with the implicit referent involved in the English usage of "it". The need for assignment comes from the need for a name. You could actually deal with the if-or-while-expression-assignment case by defining a special variable __it__ to mean the value of the condition in the containing if or while expression, but it has all the same lack of generality issues as any proposal that limits itself to if/while conditions. And short of explicitly marking the expression somehow, you can't generalise any further.

This is reminiscent of Perl's $_ variable, which represents the "current topic". http://www.perl.com/pub/2002/10/30/topic.html

On Sun, Jan 22, 2012 at 1:24 PM, Edward Lesmes <ehlesmes@gmail.com> wrote:

why not make python do something like _ = test() if _:     ... Automatically, so you can do something like

if test():     frobulate(_)

It seems natural to me, because in prompt, python assigns the last result to the _ variable

I think "Explicit is better than implicit"[0] pretty much covers why that sort of thing is generally disfavored. Cheers, Chris -- [0]: http://www.python.org/dev/peps/pep-0020/