Re: Creating a hash of arrays from row data

[Sudarshan Raghavan]

Robin Norwood wrote:

To sort-of change the subject, I think the 'deep_copy' subroutine
quoted in this article contains a bug... the sub in question:
sub deep_copy {
 my $this = shift;
 if (not ref $this) {
   $this;
 } elsif (ref $this eq "ARRAY") {
   [map deep_copy($_), @$this];
 } elsif (ref $this eq "HASH") {
   +{map { $_ => deep_copy($this->{$_}) } keys %$this};
 } else { die "what type is $_?" }
}


The next-to-last line should be:

 } else { die "what type is $this?" }

Since '$this' is the thing we're testing for what sort of reference it
is, not '$_'.
Test code:

#!/usr/bin/perl

use strict;
use warnings;
my $foo = 5;
my $bar = \$foo; # a scalar ref
my $baz = deep_copy($bar);

__END__

With the deep_copy sub above, gives the following error:

$ perl perl/deep_copy.pl
Use of uninitialized value in concatenation (.) or string at perl/deep_copy.pl line 19.
what type is ? at perl/deep_copy.pl line 19.
While with the corrected line gives the following (correct) error:

$ perl perl/deep_copy.pl
what type is SCALAR(0x8107e04)? at perl/deep_copy.pl line 20.
Unless I'm missing something.  Comments?

You are right, the last line should be
} else { die "what type is $this?" }
-RN

 



--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]