Beefy Boxes and Bandwidth Generously Provided by pair Networks
Just another Perl shrine
 
PerlMonks  

Re^2: qr/STRING/ fails with certain lookbehind expressions

by Anonymous Monk
on Jul 22, 2013 at 14:54 UTC ( #1045666=note: print w/ replies, xml ) Need Help??


in reply to Re: qr/STRING/ fails with certain lookbehind expressions
in thread qr/STRING/ fails with certain lookbehind expressions

thanks a lot for your quick explanations and advices. I wasn't aware that regexp would change my expression internally into something else (and I am actually not sure if I want that). But I kind of see the problem now (as beeing a German).

The German sharp s '' doesn't exist as a capital letter in German writing. Since no German word starts with a sharp s, there is no need for a capital accordance. If used never the less in capital writing, it is written as 'SS'. So at least from a 'German point of view' it makes sense that the 'ss' extension is only implemented for the case-insensitive modifier.

Still it is not quite clear to me what happens to the 'st' example:

my $pattern = "(?<!st)abc"; # 'st' in lookbehind qr/$pattern/i; # error: 'Variable length lookbehind not imple +mented in regex...

Whereas this one works (just like any other letter after 's' besides the combination 'ss' and 'st'):

my $pattern = "(?<!sz)abc"; # 'sz' in lookbehind qr/$pattern/i; # this works fine

Is there a way to display exactly the expression, that the regexp engine is using? (So, according to Corion this would be: /(?<!|st)abc/i in the first example). That would be very helpful.


Comment on Re^2: qr/STRING/ fails with certain lookbehind expressions
Select or Download Code
Re^3: qr/STRING/ fails with certain lookbehind expressions
by choroba (Canon) on Jul 22, 2013 at 15:04 UTC
    "st" ("st") is similar to "ss" - in certain typefaces, it is replaced by a Typographic_ligature. See also its Unicode codepoint.
    لսႽ ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1045666]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others drinking their drinks and smoking their pipes about the Monastery: (8)
As of 2015-07-07 00:03 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (85 votes), past polls