I'm surprized with \L, \l, \U and \u, are you too? :-)

Serge314 has asked for the wisdom of the Perl Monks concerning the following question:

Does the operators \L \l \U and \u have right to left associativity, or vice versa?
I think, the operators must have right to left associativity as =.
Have the operators such property as a priority?

print "\u\LdD\n";   # Dd   It seems, first works \L, then \u. Good.
print "\u\la\n";    # A  First \l, then \u. Good!
print "\l\ua\n";    # a  First \u, then \l. Good!!
print "\L\udD\n";   # Dd   It seems, first works \L, then \u, hm...
print "\LdD\udD\n"; # dddd  It seems, first works \u, then \L, hmmm...

print "\L\Ua\n";    # Syntax error
print "\U\La\n";    # Syntax error
print "\L\La\n";    # Syntax error
print "\u\la\n";    # A  All right
print "\u\ua\n";    # A  All right
[download]

Surprized? I'm again...
How we should understand work of these operators?
Should I submit a bug report? :-)

Comment on I'm surprized with \L, \l, \U and \u, are you too? :-) Download Code

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Re: I'm surprized with \L, \l, \U and \u, are you too? :-) by Anonymous Monk on Feb 21, 2011 at 09:20 UTC
See http://perl5.git.perl.org/perl.git/blob?f=t/op/lc.t http://perl5.git.perl.org/perl.git/blob?f=t/op/lc_user.t and rewrite your test case as an actual test, then submit a report with perlbug (the syntax errors are actual bugs, i'm assuming there are others)	[reply]
Re^2: I'm surprized with \L, \l, \U and \u, are you too? :-) by Serge314 (Acolyte) on Feb 21, 2011 at 15:14 UTC
Oh, it's easier to eat 1 kg salt, than to understand, how to use perlbug... I simple write an email to perlbug(a)perl.org. Here's my ticket: http://rt.perl.org/rt3/Ticket/Display.html?id=84578	[reply]
Re: I'm surprized with \L, \l, \U and \u, are you too? :-) by ikegami (Patriarch) on Feb 21, 2011 at 08:58 UTC
So it acts like list ops, with special rules to do the right thing when there are adjacent escapes. What would be gained by changing the behaviour? I'd suggest a documentation patch instead.	[reply]
Re^2: I'm surprized with \L, \l, \U and \u, are you too? :-) by Anonymous Monk on Feb 21, 2011 at 09:46 UTC
So it acts like list ops, with special rules to do the right thing when there are adjacent escapes. Um, I'm not sure what you mean by that, the behavior appears inconsistent `use Test::More qw' tests 2 '; is( "\LA\uA", "??", '\LA\uA' ); is( "\L\uAA", "??", '\L\uAA' ); __END__ 1..2 not ok 1 - \LA\uA # Failed test '\LA\uA' # at crap line 2. # got: 'aa' # expected: '??' not ok 2 - \L\uAA # Failed test '\L\uAA' # at crap line 3. # got: 'Aa' # expected: '??' # Looks like you failed 2 tests of 2.` [download] The way I read perlop they should both result in aa. Or to be a consistent special case, both should result with one character uppercased.	[reply] [d/l]
Re^3: I'm surprized with \L, \l, \U and \u, are you too? :-) by ikegami (Patriarch) on Feb 21, 2011 at 10:19 UTC
\L\u makes no sense (would be the same as just \L), so Perl treats it as \u\L (which was surely the intended effect).	[reply]
Re^4: I'm surprized with \L, \l, \U and \u, are you too? :-) by Anonymous Monk on Feb 21, 2011 at 10:38 UTC
Re^5: I'm surprized with \L, \l, \U and \u, are you too? :-) by ikegami (Patriarch) on Feb 21, 2011 at 19:42 UTC
Some notes below your chosen depth have not been shown here
Re^3: I'm surprized with \L, \l, \U and \u, are you too? :-) by Anonymous Monk on Feb 21, 2011 at 09:54 UTC
To clarify , if as perlop states `"\Q\t\E" is converted to quotemeta("\t"),` [download] shouldn't both `"\LA\uA" be converted to lc( "A\uA" ) "\L\uAA" be converted to lc( "\uAA" )` [download]	[reply] [d/l] [select]