possible bug in re expression?

Fri Apr 25 14:32:30 EDT 2014

On 4/25/2014 12:30 PM, Robin Becker wrote:
> Whilst translating some javascript code I find that this
>> A=re.compile('.{1,+3}').findall(p)
>> doesn't give any error, but doesn't manage to find the strings in p that
> I want len(A)==>0, the correct translation should have been
>> A=re.compile('.{1,3}').findall(p)
>> which works fine.
>> should
>> re.compile('.{1,+3}')
>> raise an error? It doesn't on python 2.7 or 3.3.

And it should not because it is not an error. '+' means 'match 1 or more 
occurrences of the preceding re' and the preceding re is ','.
 >>> re.match('a{1,+3}', 'a{1,,,3}').group()
'a{1,,,3}'
I suppose that one could argue that '{' alone should be treated as 
special immediately, and not just when a matching '}' is found, and 
should disable other special meanings. I wonder what JS does if there is 
no matching '}'?
-- 
Terry Jan Reedy