Re^4: regex extraction for variable number of args

Ok - it is beginning to sink in - so - it appears that there is no useful/meaningful way to combine non-capturing parens and repetition, unless your pattern starts at the beginning - in which case, you are better-off with the "/g" modifier . Or you are always better-off with the "/g" modifier.

So - is there a use case for non-capturing parens with repetition ?

I hope life isn't a big joke, because I don't get it.
-SNL

Comment on Re^4: regex extraction for variable number of args

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Re^5: regex extraction for variable number of args by Corion (Patriarch) on Jul 22, 2012 at 07:15 UTC
I can think of many uses for non-capturing parentheses with repetition. In fact, non-capturing parentheses with repetition are more sane than capturing parentheses with repetition, because the capturing parentheses will only keep the last match of the repetition. As an example a simple checker to check that a line matches a CSV-like format, using non-capturing parentheses and repetition: `$line =~ /^(?:[^,]+\|"[^"]+")(?:,(?:[^,]+\|"[^"]+"))*$/` [download] That one matches one well-formed column, and then optionally a repetition of comma and more well-formed column.	[reply] [d/l]

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Re^5: regex extraction for variable number of args
by Corion (Patriarch) on Jul 22, 2012 at 07:15 UTC

I can think of many uses for non-capturing parentheses with repetition. In fact, non-capturing parentheses with repetition are more sane than capturing parentheses with repetition, because the capturing parentheses will only keep the last match of the repetition. As an example a simple checker to check that a line matches a CSV-like format, using non-capturing parentheses and repetition:

$line =~ /^(?:[^,]+|"[^"]+")(?:,(?:[^,]+|"[^"]+"))*$/
[download]

That one matches one well-formed column, and then optionally a repetition of comma and more well-formed column.

[reply]
[d/l]