Re: Why [[:alpha:]] doesn't involve diacritic characters in replace expression?

How about if we use the character class for this?

  $str =~ s/[^[:alpha:]]//g; #i isn't needed
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I think what you found is either a bug in perl, or a bug in the documentation. [[:^alpha:]] and [^[:alpha:]] should work the same by my reading of perlre. But, apparently, it isn't working the same.

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Re^2: Why [[:alpha:]] doesn't involve diacritic characters in replace expression? by graff (Chancellor) on Oct 25, 2008 at 17:32 UTC
Thank you (++) for pointing that out, Tanktalus. Your post prompted me to do an experiment, comparing the POSIX and unicode-based "alpha" patterns (presented here as a sequence of bash shell commands). Read more... (5 kB) The `[[:^blah:]]` syntax is described in perlre as being "a Perl extension" to the POSIX syntax. My experiment shows that this extension, as applied to ":alpha:", creates a "special" class of characters, which match both ":alpha:" and ":^alpha:" -- these happen to be the "Latin1 upper-table" code points that involve letter symbols. (Using the "normal" method for inverting character classes -- `[^[:alpha:]]` -- has the expected behavior of providing the exact complement of `[[:alpha:]]`.) Maybe this could be viewed as a "feature" of the ":^alpha:" syntax, but only if people know about it. Considering that it isn't explained as such (at all) in the perlre man page -- and since it clearly differs from `[^[:alpha:]]` -- I'd have to say it's more likely to be a bug. (My experiment used perl 5.8.8 built for darwin.)	[reply] [d/l] [select]

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Re^2: Why [[:alpha:]] doesn't involve diacritic characters in replace expression?
by graff (Chancellor) on Oct 25, 2008 at 17:32 UTC

Tanktalus

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The [[:^blah:]] syntax is described in perlre as being "a Perl extension" to the POSIX syntax. My experiment shows that this extension, as applied to ":alpha:", creates a "special" class of characters, which match both ":alpha:" and ":^alpha:" -- these happen to be the "Latin1 upper-table" code points that involve letter symbols.

(Using the "normal" method for inverting character classes -- [^[:alpha:]] -- has the expected behavior of providing the exact complement of [[:alpha:]].)

Maybe this could be viewed as a "feature" of the ":^alpha:" syntax, but only if people know about it. Considering that it isn't explained as such (at all) in the perlre man page -- and since it clearly differs from [^[:alpha:]] -- I'd have to say it's more likely to be a bug. (My experiment used perl 5.8.8 built for darwin.)

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