in reply to Precedence of qw

Your greeting implies the problem is related to use strict, but it isn't. 

use warnings;
@array = qw(X) x 2;
print @array, "\n";

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gives 

Unquoted string "x" may clash with future reserved word at 541178.pl l
+ine 2.
Number found where operator expected at 541178.pl line 2, near "x 2"
        (Do you need to predeclare x?)
syntax error at 541178.pl line 2, near "qw(X) x "
Execution of 541178.pl aborted due to compilation errors.

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I've noticed this bug before.

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Re^2: Precedence of qw
by eff_i_g (Curate) on Apr 04, 2006 at 16:58 UTC
    Sorry about that; it wasn't my intent.

    I noticed something else that I posted. This: 
    #!/usr/bin/perl -w
use strict;

my $scalar = qw(A B C);
print $scalar, "\n";

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    Gives:
    Use of implicit split to @_ is deprecated at ./test27.pl line 4.
    3

    And perldiag has:
    Use of implicit split to @_ is deprecated
    (D deprecated) It makes a lot of work for the compiler when you clobber a subroutine's argument list, so it's better if you assign the results of a split() explicitly to an array (or list).

    I'm not sure how these are related...
[reply]
[d/l]

      Your version of perl probably implements
      qw(A B C)
      as
      split(' ', q(A B C))
      (although I suspect it performs said split at compile-time).

      Given the above, consider the following passage from split's documentation:

      In scalar context, returns the number of fields found and splits into the @_ array. Use of split in scalar context is deprecated, however, because it clobbers your subroutine arguments.

      If you want the count, use my $scalar = () = qw(A B C);.

      By the way, I said "your version of perl" because perl 5.6.1 gives 

      Useless use of a constant in void context at 541192.pl line 4.
Useless use of a constant in void context at 541192.pl line 4.
C

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[d/l]
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        The split is performed at runtime for perl prior to 5.6..

        ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊

[reply]

      What version of perl are you using? Mine doesn't say that at all.

      duff

[reply]
        duff, version 5.005_03 built for sun4-solaris. We have other versions on other machines; I'll try those out.
[reply]
      $ perl -w
use strict;

my $scalar = qw(A B C);
Useless use of a constant in void context at - line 3.
Useless use of a constant in void context at - line 3.
print $scalar, "\n";
C

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      $ perl -v

This is perl, v5.8.7 built for cygwin-thread-multi-64int
(with 1 registered patch, see perl -V for more detail)

      [download]
      By the way, this has nothing to do with qw. 
      $ perl -w
my $scalar = (1, 2, 3);
Useless use of a constant in void context at - line 1.

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[d/l]
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In Section Seekers of Perl Wisdom