On Fri, 22 Feb 2008 08:19:07 -0800, Carl Banks wrote:
> (The perl example wasn't using an assignment operator.)
Hmmm... I see. Obviously I didn't pretend to understand Perl well enough.
(I assume you're ignoring the assignments $name = chop(\1) etc. Fair
enough.)
[...]
> I can't help but to think that a lot of people's distaste for this
> natural way to write certain logic is simply defensiveness about one
> minor little thing that Python doesn't support (without workarounds).
But Python certainly does support set-and-test. You just have to separate
the set from the test with a newline:
m = re.match(r"name=(.*)",line) # set
if m: # test
name = m.group(1).strip()
This does the same thing as your proposed syntax
if m where m = re.match(r"name=(.*)",line):
name = m.group(1).strip()
except that it doesn't create a new scope. I'm not sure that the benefit
of having a new scope is worth the new keyword. Maybe it is, maybe it
isn't.
I think I have a better idea of what you are trying to say. Despite first
impressions, you weren't defending the proposed "assign-and-test" idiom
suggested by Stephen Gross:
pat = re.compile('some pattern')
if m = pat.match(some_string): # doesn't work in Python
do_something(m)
on account of it needing an assignment expression, which is Bad. But you
were defending the principle of set-and-test, if we can use something
other than an assignment expression to do the set.
E.g. Perl's magic syntax "if /pattern/ { }" (everything in Perl is magic
syntax), or your proposed "if m where m = expression".
Okay, I can agree with that, particularly since Python already supports
it using the plain old boring, old fashioned idiom of "assign, then test".
--
Steven
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