[Tcl-bugs] [ tcl-Bugs-1376892 ] [:print:] wrong behaviour

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Bugs item #1376892, was opened at 2005-12-09 05:23
Message generated for change (Comment added) made by dkf
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Category: 42. Regexp
Group: obsolete: 8.4.11
Status: Open
Resolution: None
>Priority: 7
Submitted By: Petteri Kettunen (petterik)
Assigned to: Pavel Goran (pvgoran)
Summary: [:print:] wrong behaviour

Initial Comment:
% set str {moi+moi+moi}
% regsub -all {[^[:print:]]} $str {} str2; puts $str2
moimoimoi

Expected result is the original string.

This, however, is subject to definition and Tcl's
specification. If one keeps `perlre' as the refence,
this is a bug. Perlre (v5.6.1) says: 'print -- Any
alphanumeric or punctuation (special) character or space.'
 

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>Comment By: Donal K. Fellows (dkf)
Date: 2006-02-16 06:53

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Bug is located at line 817 of the HEAD regc_locale.c, and
consists of a missing arm for the CC_PRINT case. I believe
that the fix required (based on the POSIX definition, thanks
Bill!) is the attached patch, which I'd appreciate people
testing... :-)

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Comment By: William John Poser (billposer)
Date: 2006-02-15 19:08

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Perhaps more important than the Perl definition is the POSIX
definition, according to which [:print:] = [:alnum:] U
[:punct:] U SPACE. Curiously, the current behaviour with
[:print:] = [:alnum:] is documented in Welch, Jones, and
Hobbs with no mention of it being a bug.


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Comment By: Donal K. Fellows (dkf)
Date: 2005-12-09 16:42

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Good point. Yes. And [string is print] follows C's isprint()
IIRC, so it is (almost certainly) the RE engine that is wrong.

OK, this should be fixed.

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Comment By: Don Porter (dgp)
Date: 2005-12-09 16:34

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should we also consider
consistency with
[string is print] ?

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Comment By: Donal K. Fellows (dkf)
Date: 2005-12-09 09:19

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It seems that Perl defines [[:print:]] as
[[:space:][:graph:]] and we define it as [[:alnum:]] (and
yes, it is documented that way.) Or perhaps [:blank:]
instead of [:space:], the documentation being a bit hazy in
that respect.

The question is, what *should* we do?

The following procedure helps with checking these sorts of
things out:
   proc matches args {
      set RE [format {[[:%s:]]} [join $args ":\]\[:"]]
      for {set i 32} {$i<127} {incr i} {
         set c [format %c $i]
         puts -nonewline "$c-[regexp $RE $c]\t"
      }
      puts ""
   }

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