Re: Non-capturing zero-width negative lookahead

The (?! is noncapturing as is.

However you have included a (:?, the colon ~~depicts an (unrecognized) regexp extension~~is not a metacharacter so this is treated as a regular capturing group.

Updated: clarified my statement, Sidhekin is right

Comment on Re: Non-capturing zero-width negative lookahead

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Re^2: Non-capturing zero-width negative lookahead by Sidhekin (Priest) on Mar 22, 2007 at 16:50 UTC
the colon depicts an (unrecognized) regexp extension No, it doesn't. The colon is a literally matching atom, and the question mark is a quantifier. With some hopefully clearer /x spacing: `$foo =~ /( ( :? . # 0 or 1 colon + 1 non-newline char \| # or \n (?! \n\n) # 1 newline not followed by two more newlin +es )+ ) /x` [download] `print "Just another Perl ${\(trickster and hacker)},"` The Sidhekin proves Sidhe did it!	[reply] [d/l] [select]

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Re^2: Non-capturing zero-width negative lookahead
by Sidhekin (Priest) on Mar 22, 2007 at 16:50 UTC

the colon depicts an (unrecognized) regexp extension

No, it doesn't. The colon is a literally matching atom, and the question mark is a quantifier. With some hopefully clearer /x spacing:

$foo =~ /( ( :? .          # 0 or 1 colon + 1 non-newline char
             |             # or
             \n (?! \n\n)  # 1 newline not followed by two more newlin
+es
            )+
          ) /x
[download]

print "Just another Perl ${\(trickster and hacker)},"
The Sidhekin proves Sidhe did it!

[reply]
[d/l]
[select]