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Re: [PATCH] Add open "|-" and open "-|" to perlopentut

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From:
Tom Christiansen
Date:
August 26, 2008 11:25
Subject:
Re: [PATCH] Add open "|-" and open "-|" to perlopentut
Message ID:
23679.1219775127@chthon
>> And so we have a culture--no, strike that--we have *two*
>> cultures, where they are expecting \t, and \n too, to mean a
>> single character.

> By that argument, you should agree with Damian's admonition that
> one should always use the `/m` modifier on patterns, because that
> will make `^` and `$` behave as programmers from other cultures
> expect, even though in Perl they behave differently, and a Perl
> programmer knows how they do behave in Perl.

First off, I confess to failing to deeply understand where Damian is 
coming from there.  Therefore, I shall neither agree nor disagree with 
what I do not understand.  Which means I cannot continue your question.

More specifically, I have myself no acquaintance with any culture where 
/^/ means /^/m.  Perhaps Damian does.  The same applies to /$/ vs /$/m.

So I am quite confortable using ^ in nearly all places, though perhaps 
not in /^[^^]/ :).

However, /$/ is trickier for a different reason altogether, and its trouble
is unimproved by /$/m, or by /\Z/ either.  It's a bit of a shame that as
/./s means /\p{Any}/ (which is what I more often use now, lamentably
unHoffmaning the commonest thing from a wee 1 to a super 7, even 8 chars),
that /$/s never came to mean /\z/.  

Given that I've had to fix this before, as noted in the Changes5.6 log entry:

[  5296] By: gsar                                  on 2000/02/28  00:00:05
        Log: m/.*$/ etc should be m/.*\z/s in many file handling modules; fix
             these insidious errors in File::Basename, File::Find and find2perl
             (from Tom Christiansen)
             
             TODO: many other modules need to be fixed as well!
     Branch: perl
           ! lib/File/Basename.pm lib/File/Find.pm x2p/find2perl.PL

There is probably something to be learned here, even if I don't quite
understand what Damian's saying.  As noted, I do hate insidious errors.

--tom

PS: Don't get me started about use warnings safety on

	\p{Any}
	\p{Assigned}
	\p{UnAssigned}

    eg% perl -WE 'say chr(0xfdd0) =~ /\p{Any}/ || 0'
    Unicode character 0xfdd0 is illegal at -e line 1.
    1

    eg% perl -WE 'say chr(0xfdd0) =~ /\p{Assigned}/ || 0'
    Unicode character 0xfdd0 is illegal at -e line 1.
    0

    eg% perl -WE 'say chr(0xfdd0) =~ /\p{UnAssigned}/ || 0'
    Unicode character 0xfdd0 is illegal at -e line 1.
    1

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