How to match word boundary?

[Peng Yu]

Hi,

I use r"\ba\b" to match "a". However, I can not use "\ba::\b" to match
"a::b".

I would like to match "a::" in "a::b", but not in "a:: b". That is,
the character after "::" should be a alphanumeric character. Could you
let me know how to do it and why "\b" would not work?

Thanks,
Peng

[Fredrik Lundh]

Re: How to match word boundary?

Peng Yu wrote:

I would like to match "a::" in "a::b", but not in "a:: b". That is,
the character after "::" should be a alphanumeric character.

sounds like a look-ahead assertion is what you need:

>>import re
>>re.match("\w: :(?=\w)", "a::b")

<_sre.SRE_Mat ch object at 0x01442138>

>>_.group()

'a::'

>>re.match("\w: :(?=\w)", "a:: b")
>>>

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