in reply to Surprise: scalar(($x, $y) = split)

Update: Everything below is wrong, as ambrus mentions in the reply. (Note to self: Self, just because you get the correct result doesn't mean that you got the right answer!)

ambrus:

You forgot some parenthesis:

(2==(my($x,$y) = split " ")) or die "wrong number of fieldsd";

Example:

$ cat foo.pl
use strict;
use warnings;
my $x; my $y;
while (<DATA>) {
    chomp;
    (2==0+(($x, $y) = split /:/,$_)) or print "wrong number of fields\
+n";
    print "<$_>, <$x>, <$y>\n";
}
__DATA__
FOO:BAR:BAZ:PLOVE
FOO:BAR:BAZ
FOO:BAR
BAZ
$ perl foo.pl
wrong number of fields
<FOO:BAR:BAZ:PLOVE>, <FOO>, <BAR>
wrong number of fields
<FOO:BAR:BAZ>, <FOO>, <BAR>
<FOO:BAR>, <FOO>, <BAR>
wrong number of fields
Use of uninitialized value $y in concatenation (.) or string at foo.pl
+ line 7, <DATA> line 4.
<BAZ>, <BAZ>, <>

[download]

...roboticus

When your only tool is a hammer, all problems look like your thumb.

Replies are listed 'Best First'.
Re^2: Surprise: scalar(($x, $y) = split)
by ambrus (Abbot) on Oct 28, 2011 at 14:05 UTC

    It's not the parenthesis that helps there but

    the chomp. 
    $ perl -e 'warn 0+(($x, $y) = split " ", "foo bar\n");'
3 at -e line 1.
$ perl -e 'warn 0+(($x, $y) = split " ", "foo bar");'
2 at -e line 1.

    [download]
[reply]
[d/l]

      ambrus:

      Ha, ha--color me surprised as well!

      Corrected example:

      $ cat foo.pl
use strict;
use warnings;
my $x; my $y;
while (<DATA>) {
    chomp;
    2==(($x, $y) = split " ") or print "wrong number of fields\n";
    print "<$_>, <$x>, <$y>\n";
}
__DATA__
FOO BAR BAZ PLOVE
FOO BAR BAZ
FOO BAR
BAZ
$ perl foo.pl
wrong number of fields
<FOO BAR BAZ PLOVE>, <FOO>, <BAR>
wrong number of fields
<FOO BAR BAZ>, <FOO>, <BAR>
<FOO BAR>, <FOO>, <BAR>
wrong number of fields
Use of uninitialized value $y in concatenation (.) or string at foo.pl
+ line 7, <DATA> line 4.
<BAZ>, <BAZ>, <>

      [download]

      ...roboticus

      When your only tool is a hammer, all problems look like your thumb.

[reply]
[d/l]

In Section Meditations