affectation in if statement
Hi,
I'm trying to do something like :
if m = re.match(r'define\s+(\S+)\s*{$', line):
thing = m.group(1)
elif m = re.match(r'include\s+(\S+)$', line):
thing = m.group(1)
else
thing = ""
But in fact I'm not allowed to affect a variable in "if" statement.
My code should then look like :
if re.match(r'define\s+(\S+)\s*{$', line):
m = re.match(r'define\s+(\S+)\s*{$', line)
thing = m.group(1)
elif re.match(r'include\s+(\S+)$', line):
m = re.match(r'include\s+(\S+)$', line)
thing = m.group(1)
else
thing = ""
Which is not nice because I'm doing twice the same instruction
or like :
m = re.match(r'define\s+(\S+)\s*{$', line)
if m:
thing = m.group(1)
else:
m = re.match(r'include\s+(\S+)$', line)
if m:
thing = m.group(1)
else
thing = ""
Which isn't nice neither because I'm going to have maybe 20 match
tests and I wouldn't like to have 20 indentations.
Anyone a recommendation?
Thanks!
--
http://mail.python.org/mailman/listinfo/python-list
Re: affectation in if statement
Thanks for all those suggestions.
They are good!
1) Let's suppose now that instead of just affecting "thing =
m.group(1)", I need to do a piece of logic depending on which match I
entered...
2) Concerning the suggestion :
m = re.match(r'define\s+(\S+)\s*{$', line)
if m:
thing = m.group(1)
m = re.match(r'include\s+(\S+)$', line)
if m:
thing = m.group(1)
#etc...
It means that I'll do all the checks, even if the first one did match
and I know that the next will not...
Thanks again.
--
http://mail.python.org/mailman/listinfo/python-list
Re: affectation in if statement
On Mar 16, 9:53 am, Chris Rebert wrote:
> On Tue, Mar 16, 2010 at 1:37 AM, samb wrote:
> > Thanks for all those suggestions.
> > They are good!
>
> > 2) Concerning the suggestion :
> > m = re.match(r'define\s+(\S+)\s*{$', line)
> > if m:
> > thing = m.group(1)
>
> > m = re.match(r'include\s+(\S+)$', line)
> > if m:
> > thing = m.group(1)
>
> > #etc...
>
> Note how I split it out into a separate function and used `return
> m.group(1)` to avoid that exact situation.
Yes, you're right.
It's an interresting approach. I'll give it a try.
Cheers
--
http://mail.python.org/mailman/listinfo/python-list
Re: affectation in if statement
Hi,
I've found a work around, inspired from Rob Williscroft :
class ReMatch(object):
"""
Object to be called :
1st time : do a regexp.match and return the answer (args:
regexp, line)
2nd time : return the previous result (args: prev)
"""
def __call__(self, regexp='', line='', prev=False):
if prev:
return self.prev_match
self.prev_match = re.match(regexp, line)
return self.prev_match
re_match = ReMatch()
if re_match(r'define\s+(\S+)\s*{$', line):
m = re_match(prev=True)
# do some logic with m
elif re_match(r'include\s+(\S+)$', line):
m = re_match(prev=True)
# do some logic with m
else
# do some logic
Hope this is efficient ... I guess yes.
Cheers,
Sam
--
http://mail.python.org/mailman/listinfo/python-list
Re: affectation in if statement
On Mar 16, 11:56 am, Jean-Michel Pichavant
wrote:
> samb wrote:
> > Hi,
>
> > I've found a work around, inspired from Rob Williscroft :
>
> > class ReMatch(object):
> > """
> > Object to be called :
> > 1st time : do a regexp.match and return the answer (args:
> > regexp, line)
> > 2nd time : return the previous result (args: prev)
> > """
> > def __call__(self, regexp='', line='', prev=False):
> > if prev:
> > return self.prev_match
> > self.prev_match = re.match(regexp, line)
> > return self.prev_match
>
> > re_match = ReMatch()
>
> > if re_match(r'define\s+(\S+)\s*{$', line):
> > m = re_match(prev=True)
> > # do some logic with m
> > elif re_match(r'include\s+(\S+)$', line):
> > m = re_match(prev=True)
> > # do some logic with m
> > else
> > # do some logic
>
> > Hope this is efficient ... I guess yes.
>
> > Cheers,
> > Sam
>
> What do you mean by efficient ? If you're talking about speed, make sure
> you care about it before doing some optimization.
> If you talk about readability then it is absolutely *not* efficient (to
> my humble opinion).
>
> define, include = re.match(r'define\s+(\S+)\s*{$', line),
> re.match(r'include\s+(\S+)$', line)
> if define:
> # do some stuff
> elif include:
> # do some other stuff
> else:
> # hello world
>
> If you then have some speed problem with that script, you'll start
> caring about how to execute if faster by making sure that only necessary
> calls to re.match are done.
>
> match = re.match(r'(define)\s+(\S+)\s*{$', line) or
> re.match(r'(include)\s+(\S+)$', line) # note that the second operand is
> executed only if the first is None
>
> if match.group(1) == 'define':
> # do some stuff with match.group(2)
>
> elif match.group(1) == 'include':
> # do some other stuff with match.group(2)
>
> else:
> # hello world
>
> JM
Hi,
Thanks Bruno for the simpler API!
And thanks Jean-Michel, your second suggestion is clearly the best I
see.
I meant efficient mainly in the readable aspect (important for future
maintenance) and secondary for speed of execution. For sure I didn't
want to run a regexp twice.
Regards,
Sam
--
http://mail.python.org/mailman/listinfo/python-list
