croak not like die.

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

If its message parameter ends in a new line, die WILL NOT add the line number to the end of the string. Croak is suppose to be similar to die. However, If its message parameter ends in a new line, croak WILL add the line number to the end of the string. Why is that? Is this a bug or did they mean to do that?

The following program illustrates the difference.

#!/usr/bin/perl -w
use Carp;

eval {
  eval {
    die "Pig\n";
  };
  if ($@) { print $@."\n"; die $@; }
};
print $@ if $@;

eval {
  eval {
    croak "Pig\n";
  };
  if ($@) { print $@."\n"; croak $@; }
};
print $@ if $@;
[download]

On my machine, it returns ...

Pig

Pig
Pig
        eval {...} called at ./test7.pl line 13
        eval {...} called at ./test7.pl line 12

Pig
        eval {...} called at ./test7.pl line 13
        eval {...} called at ./test7.pl line 12
        eval {...} called at ./test7.pl line 12
[download]

Comment on croak not like die. Select or Download Code

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Re: croak not like die. by brian_d_foy (Abbot) on Mar 16, 2005 at 19:11 UTC
Your sample program is a bit convoluted to be useful, so I wrote my own: `#!/usr/bin/perl use Carp; eval { croak "With a newline\n" }; print $@; eval { croak "No newline" }; print $@;` [download] Here's my output on perl v5.8.4 built for darwin-2level. With a newline, there is nothing after the message "With a newline", although croak still tell me where it happened. After the message "No newline", I get the file name and line number, and croak still tells me a little bit about where this happened. `With a newline eval {...} called at croak.pl line 5 No newline at croak.pl line 7 eval {...} called at croak.pl line 7` [download] This is the output I expect: If I'm using croak(), I want that information about the caller. That's a separate issue from tacking on the filename and line number though. -- brian d foy <bdfoy@cpan.org>	[reply] [d/l] [select]
Re: croak not like die. by RazorbladeBidet (Friar) on Mar 16, 2005 at 18:57 UTC
This is what I got: `perl -MCarp -le 'croak "Died here"' Died here at -e line 1` [download] vs. `perl -MCarp -le 'croak "Died here\n"' Died here` [download] from the perldoc: The Carp routines are useful in your own modules because they act like die() or warn(), but with a message which is more likely to be useful to a user of your module. soooo.... it's not the same, but like. -------------- It's sad that a family can be torn apart by such a such a simple thing as a pack of wild dogs	[reply] [d/l] [select]
Re^2: croak not like die. by holli (Abbot) on Mar 16, 2005 at 19:14 UTC
I get `Pig Pig Pig at C:\t.pl line 14 eval {...} called at C:\t.pl line 13 eval {...} called at C:\t.pl line 12 Pig at C:\t.pl line 14 eval {...} called at C:\t.pl line 13 eval {...} called at C:\t.pl line 12 at C:\t.pl line 16 eval {...} called at C:\t.pl line 12` [download] (ActivePerl 5.8.6) holli, /regexed monk/	[reply] [d/l]
Re^2: croak not like die. by Joost (Canon) on Mar 16, 2005 at 22:53 UTC
I get `> perl -MCarp -le 'croak "Died here"' Died here at -e line 1 > perl -MCarp -le 'croak "Died here\n"' Died here at -e line 1` [download] Which is not the same as your ouput, but I would consider mine better, since the reason to use croak is to give the file/line message in the first place. This is perl, v5.8.6 built for i686-linux. (with -DDEBUGGING by the way, though I doubt that matters.) "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l]