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How to do this in Python...

Erik Max Francis max at alcyone.com
Thu Jan 23 19:58:26 EST 2003 
Michael Tiller wrote:

> I'm puzzled by what seems like a missing piece of functionality in
> Python.
> I suspect there is a simple way to do what I want to do and I'm
> guessing
> someone here can point it out to me.  Here is the issue:
> 
> In C++, I could write a statement like this:
> 
> if (match=re.match(pattern, string))
>   // do something with the match object
> 
> But I cannot figure out how to do the equivalent thing in Python.

You cannot (without winning obfuscation contests, anyway).  Assignment
is a statement, and if expects expressions.  This was done as a
deliberate act to avoid the common newbie mistake in C or C++ of writing

	if (a = b) ...

when you meant

	if (a == b) ...

Whether or not you agree with the philosophy behind the decision, it's
in the language.  The Pythonic way to do the same thing is an assignment
and then a separate test:

	a = b
	if a: ...

-- 
 Erik Max Francis / max at alcyone.com / http://www.alcyone.com/max/
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/  \ An undevout astronomer is mad.
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