On May 21, 4:38 am, [EMAIL PROTECTED] wrote:
> Hello,
>
> I have an if-elif chain in which I'd like to match a string against
> several regular expressions. Also I'd like to use the match groups
> within the respective elif... block. The C-like idiom that I would
> like to use is this:
>
> if (match = my_re1.match(line):
> # use match
> elsif (match = my_re2.match(line)):
> # use match
> elsif (match = my_re3.match(line))
> # use match
>
> ...buy this is illegal in python. The other way is to open up an else:
> block in each level, do the assignment and then the test. This
> unneccessarily leads to deeper and deeper nesting levels which I find
> ugly. Just as ugly as first testing against the RE in the elif: clause
> and then, if it matches, to re-evaluate the RE to access the match
> groups.
>
> Thanks,
> robert
Try this.
-- Paul
class TestValue(object):
"""Class to support assignment and test in single operation"""
def __init__(self,v=None):
self.value = v
"""Add support for quasi-assignment syntax using '<<' in place of
'='."""
def __lshift__(self,other):
self.value = other
return bool(self.value)
import re
tv = TestValue()
integer = re.compile(r"[-+]?\d+")
real = re.compile(r"[-+]?\d*\.\d+")
word = re.compile(r"\w+")
for inputValue in ("123 abc 3.1".split()):
if (tv << real.match(inputValue)):
print "Real", float(tv.value.group())
elif (tv << integer.match(inputValue)):
print "Integer", int(tv.value.group())
elif (tv << word.match(inputValue)):
print "Word", tv.value.group()
Prints:
Integer 123
Word abc
Real 3.1
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