tcf03 has asked for the wisdom of the Perl Monks concerning the following question:

Odd to me anyway... 
perl -Mstrict -e'my $num = 1; print 1 if $num >= 1; print 2 if $num =>
+ 1;'

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Works as I'd expect. As does The following code does what Id expect. 
#!/usr/bin/perl

use strict;
use warnings;
use Carp;
use DBI;
use Data::Dumper;

# Connection
my $dsn = qq|dbi:Informix:sysmaster|;
my $dbh = DBI->connect($dsn) or confess DBI->errstr();
$dbh->{'RaiseError'} = 1;
$dbh->{'ChopBlanks'} = 1;

# Hash to hold all info about tables...
my %dbinfo;

# Get info on extents...
{
    my $query = qq|select count(*), tabname
                   from sysextents
                   group by tabname|;

    my $sth = $dbh->prepare($query) or confess DBI->errstr();

    $sth->execute or confess DBI->errstr();

    my ( $count, $table );

    $sth->bind_col(1, \$count);
    $sth->bind_col(2, \$table);

    while ( $sth->fetchrow )
    {
        next unless $count >= 8;
        $dbinfo{$table}{'extents'} = $count;
    }
}

print Dumper %dbinfo;

END { $dbh->disconnect }

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which outputs
__snip__ 
$VAR77 = 'abcde';
$VAR78 = {
           'extents' => 14
         };
$VAR79 = 'abcdef';
$VAR80 = {
           'extents' => 33
         };
$VAR81 = 'abcdefg';
$VAR82 = {
           'extents' => 93
         };
$VAR83 = 'abcdefgh';
$VAR84 = {
           'extents' => 17
         };

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but when I change line 35 to 
next unless $count => 8;

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I get all table extents returned.
__snip__ 
$VAR2949 = 'abcdefgh';
$VAR2950 = {
             'extents' => '4'
           };
$VAR2951 = 'abcdefghi';
$VAR2952 = {
             'extents' => '1'
           };
$VAR2953 = 'abcdefghij';
$VAR2954 = {
             'extents' => '1'
           };
$VAR2955 = 'abcdefghz';
$VAR2956 = {
             'extents' => '1'
           };
$VAR2957 = 'abcdefghp';
$VAR2958 = {
             'extents' => '1'
           };
$VAR2959 = 'abcde';
$VAR2960 = {
             'extents' => '1'
           };
$VAR2961 = 'abcderr';
$VAR2962 = {
             'extents' => '1'
           };
$VAR2963 = 'abcdewe';
$VAR2964 = {
             'extents' => '1'
           };

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Just curious as to the why of this.

perl is old ( nothing I can do about it either, upgrades are scheduled ), Output of perl -v is 
This is perl, v5.8.3 built for x86_64-linux-thread-multi

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updateupdated mis-spelled node title...

update2
The command line example is actually the odd behavior. So to restate my question, why does that output 12?

update3If I could only -- myself, I would, on this one. Whats the point of use warnings; if you don't read them?
Ted
--
"That which we persist in doing becomes easier, not that the task itself has become easier, but that our ability to perform it has improved."
  --Ralph Waldo Emerson

Replies are listed 'Best First'.
Re: odd =>behavior
by Fletch (Bishop) on Dec 04, 2007 at 17:23 UTC

    Erm, is it just me or do you seem to be confuzzling the fat comma => with the numeric lessgreater-than-or-equals operator >=? You're basically asking if a LIST in boolean context is true (which your list is, so you get all the elements).

    Update: Lesser, greater. Something about alligators. Meh. :)

    The cake is a lie.
    The cake is a lie.
    The cake is a lie.

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[select]
      I think I have in fact done that. In my original code, I had fat fingered => ( in lieu of >= ) I had a few moments and was playing with => vs >= on the command line. My first example, using => and >=, outputs 12. So based on that behavior, I would have expected the same to happen in my code.

      Ted
      --
      "That which we persist in doing becomes easier, not that the task itself has become easier, but that our ability to perform it has improved."
        --Ralph Waldo Emerson
[reply]

        In your first example you have $num which is greater-than-or-equal to 1, so that prints the 1; you also have (in effect) print 2 if 2 which again is always true so it's always going to print.

        When you change your conditional in the later code to print unless $count => 8 you effectively have print unless 8, which will always be true hence you get all elements.

        The cake is a lie.
        The cake is a lie.
        The cake is a lie.

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Re: odd =>behavior
by toolic (Bishop) on Dec 04, 2007 at 17:32 UTC
    Do you not get the following kind of warning when you use the fat comma in your code?
    Useless use of private variable in void context at...
    I get the warning when I run this code (v5.8.0 built for x86_64-linux-thread-multi): 
    #!/usr/bin/env perl

use warnings;
use strict;

my $count = 9;
my $i = 0;
while ($i<5) {
    next unless $count => 8;
    $i++;
}
print "end\n";

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    The "=>" operator is described in perlop as:
    The => operator is a synonym for the comma, but forces any word (consisting entirely of word characters) to its left to be interpreted as a string (as of 5.001). This includes words that might otherwise be considered a constant or function call.
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[d/l]
      Yes, I am seeing the warning now. after adjusting the size of my scroll back buffer, I see it fine. I feel like a n00b
      Ted
      --
      "That which we persist in doing becomes easier, not that the task itself has become easier, but that our ability to perform it has improved."
        --Ralph Waldo Emerson
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Re: odd =>behavior
by grep (Monsignor) on Dec 04, 2007 at 17:24 UTC
     => is the Fat Comma - basically a comma that quotes the LHS.
     >= is Greater than or equal to

    Check out perlop

    UPDATE:
    Just remember it's consistent between > and <. The > or < always comes before the equals(=) sign.

    grep
    One dead unjugged rabbit fish later...
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Re: odd =>behavior
by jrsimmon (Hermit) on Dec 04, 2007 at 17:26 UTC
    I don't quite understand your use of the => operator.
    if($var => digit) is always undefined does not evaluate $var in relation to digit. If you mean, "greater than or equal to", then your first example of >= is the correct syntax.

    Update: Corrected statement above, as pointed out by Fletch.
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      No, if( $var => 2 ) { ... } is the same as if( $var, 2 ) { ... }, and a LIST in scalar context is the last element from the list. There's nothing undefined about it.

      The cake is a lie.
      The cake is a lie.
      The cake is a lie.

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        a LIST in scalar context is the last element from the list.

        Not always:

        sub return_list { return 3, 2, 1 }

my $result = return_list();
print "$result\n";

$result = 3, 2, 1;
print "$result\n";

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