I often have the need to match multiple regexes against a single
string, typically a line of input, like this:
if (matchobj = re1.match(line)):
... re1 matched; do something with matchobj ...
elif (matchobj = re2.match(line)):
... re2 matched; do something with matchobj ...
elif (matchobj = re3.match(line)):
....
Of course, that doesn't work as written because Python's assignments
are statements rather than expressions. The obvious rewrite results
in deeply nested if's:
matchobj = re1.match(line)
if matchobj:
... re1 matched; do something with matchobj ...
else:
matchobj = re2.match(line)
if matchobj:
... re2 matched; do something with matchobj ...
else:
matchobj = re3.match(line)
if matchobj:
...
Normally I have nothing against nested ifs, but in this case the deep
nesting unnecessarily complicates the code without providing
additional value -- the logic is still exactly equivalent to the
if/elif/elif/... shown above.
There are ways to work around the problem, for example by writing a
utility predicate that passes the match object as a side effect, but
that feels somewhat non-standard. I'd like to know if there is a
Python idiom that I'm missing. What would be the Pythonic way to
write the above code?
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