Re^6: about style: use possessive or atomic?

> but friend wrote to me, that with perl 5.20 he gained something wrong (warning/error).

Couldn't you make this clear from the beginning?

> don't have access to code,

Then please reproduce it next time.

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)

Je suis Charlie!}

Comment on Re^6: about style: use possessive or atomic?

Replies are listed 'Best First'.
Re^7: about style: use possessive or atomic? by rsFalse (Chaplain) on Aug 16, 2015 at 22:16 UTC
To by honest, I don't remember. And it is possible that I used that construct redundantly or I used it with wrong faith that after possessive quantifier succeeds then all backtrackings are disabled from this point (but for real backtrackings are disabled only in that group). Today I failed to imagine practical example where this atomic/possessive construct could be used.	[reply]
Re^7: about style: use possessive or atomic? by rsFalse (Chaplain) on Aug 17, 2015 at 17:19 UTC
So I accessed today to the code. It was a regular expression which tries to match (number1) with (measuring units1){optional}, and (number2 with units2){optional}. The shortened for simplicity regex looks like that: `/^ (?: ' \s* )? ($positive_number){1}+ \s* (?: $ \s* ($stdev) \s* $ )? \s* ($units_1)? ( \s* ($positive_number) \s* (?: $ \s* ($stdev) \s* $ )? \s* ($units_2) )? (?: \s* ' )? $/x` [download] For example: `$units_1 = "A\|B3"; $units_2 = "C\|D-3";` Then regex should match: `20B3 20 B3 15 D-3 20A15C` [download] but it shouldn't match `20C`. With new backtracking it matches 20C as (2, undef, undef, 0, undef, C) === ($1, $2, $3, $4, $5, $6)	[reply] [d/l] [select]
Re^8: about style: use possessive or atomic? by LanX (Saint) on Aug 17, 2015 at 19:28 UTC
Well the question seems answered now, its a bug from 5.20 onwards. `(?>...)` still works like expected (and its better readable IMHO) Seems like someone thought there should be a (erroneous) warning and patched the code. The perldoc mentioning redundancy might have paved the way for accepting this patch too easily. I'm surprised there was no unit test that alarmed p5p. Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply] [d/l]