Re^2: Why are elements of my array getting deleted?

Thanks for the advice, your were on the right track. I was iterating over @plist in a foreach loop, as shown in the script example I posted above. There's definitely something funny going on with the $_ variable in that loop. I was able to get a workaround going, shown below, by replacing the foreach loop with a for loop. In my larger script, I simply index into @plist when necessary using $idx.

use strict;
use IPC::Open3;

my @plist = ("ABC","DEF","GHI");

print "plist Before ccmexec:\n============\n",join("\n",@plist),"\n===
+=========\n\n";

my $ccmexecResult;
my $idx = 0;
for ($idx = 0; $idx <= $#plist;$idx++){
    $ccmexecResult = ccmexec_nodie("echo HelloWorld");
    
    print "ccmexec returned: $ccmexecResult\n";
    print "plist After ccmexec:\n============\n",join("\n",@plist),"\n
+============\n\n";
}

sub ccmexec_nodie {
    my $command = $_[0];
      
    my ($mystdin,$mystdout,$mystderr);
    my $pid = open3($mystdin,$mystdout,$mystderr,$command);
   
    my $myresult = "";
    while(<$mystdout>){
         $myresult = "$myresult$_";
    }
  
    return $myresult;
}
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Re^3: Why are elements of my array getting deleted? by GrandFather (Saint) on Apr 19, 2012 at 01:02 UTC
ARGH, no, don't do that! Actually by now you've probably already seen my earlier reply. Argel was exactly right and the suggested fix of using an explicit variable in place of the default variable is a much better solution than resorting to a C style for loop. As an aside for and foreach are aliases in Perl. It is the syntax that distinguishes between the Perlish iterating over a list behaviour and the Cish for loop behaviour. Personally I use for in both cases because I'm lazy and can't be bothered typing the superfluous "each". The important lesson to learn from this is that the special variables are effectively globals and may change without notice, especially during the processing of a called subroutine. The default variable is most prone to this issue and should be avoided where possible in any non-trivial script. True laziness is hard work	[reply]

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Re^3: Why are elements of my array getting deleted?
by GrandFather (Saint) on Apr 19, 2012 at 01:02 UTC

ARGH, no, don't do that! Actually by now you've probably already seen my earlier reply. Argel was exactly right and the suggested fix of using an explicit variable in place of the default variable is a much better solution than resorting to a C style for loop.

As an aside for and foreach are aliases in Perl. It is the syntax that distinguishes between the Perlish iterating over a list behaviour and the Cish for loop behaviour. Personally I use for in both cases because I'm lazy and can't be bothered typing the superfluous "each".

The important lesson to learn from this is that the special variables are effectively globals and may change without notice, especially during the processing of a called subroutine. The default variable is most prone to this issue and should be avoided where possible in any non-trivial script.

True laziness is hard work

[reply]