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!
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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.
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Re: affectation in if statement
On Mar 16, 9:53 am, Chris Rebert c...@rebertia.com wrote:
On Tue, Mar 16, 2010 at 1:37 AM, samb sam.ban...@gmail.com wrote:
Thanks for all those suggestions.
They are good!
snip
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
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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
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Re: affectation in if statement
On Mar 16, 11:56 am, Jean-Michel Pichavant jeanmic...@sequans.com
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
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