affectation in if statement

Chris Rebert clp2 at rebertia.com
Tue Mar 16 08:58:23 CET 2010


On Tue, Mar 16, 2010 at 12:45 AM, samb <sam.bancal at gmail.com> wrote:
> 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?

def extract_thing(line):
    for regex in (r'define\s+(\S+)\s*{$', r'include\s+(\S+)$'):
        m = re.match(regex, line)
        if m: return m.group(1)
    return ""

Or if the real code is more complicated than your example:

def extract_thing(line):
    m = re.match(r'define\s+(\S+)\s*{$', line)
    if m: return m.group(1)

    m = re.match(r'include\s+(\S+)$', line)
    if m: return m.group(1)

    #etc...

    return ""

Cheers,
Chris
--
http://blog.rebertia.com



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