in reply to Re: At which line number did the print statement occur?
in thread At which line number did the print statement occure?

Another good one to remember is __FILE__.

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Re^3: At which line number did the print statement occure?
by jeanluca (Deacon) on Oct 13, 2006 at 13:41 UTC
    or $0
    Do you know where are all the __LINE__, __FILE__ or __PACKAGE__ documented ?

    Thnx!
[reply]

      $0 and __FILE__ are subtly different. $0 will only ever contain the name of the program that is running. If the program calls code in other files (modules, for example) then __FILE__ will have different values.

      These values are documented in the section on "Special Literals" in perldata.

      --
      <http://dave.org.uk>

      "The first rule of Perl club is you do not talk about Perl club."
      -- Chip Salzenberg

[reply]

        The distinction between $0 and __FILE__ is handy. You can use it to implement unit tests for classes. I do this a lot in Ruby. For example, in classFoo.pm:

        #/usr/bin/perl
package Foo;

sub new {
  # ...
}

# other stuff

if (__FILE__ eq $0) {
  my $foo = new Foo;
  # test foo's methods, etc
}

1;

        [download]

        Now you'll only get the unit tests if you run classFoo.pm directly, because otherwise, __FILE__ ne $0.

        Of course, I must recommend using Test::More and friends instead. Just showing a possible application of the subtle difference between __FILE__ and $0.

[reply]
[d/l]
[select]
      man perldata, which, unless you know much about the Perl internals, is an unlikely place to look. I had to use grep on the POD directory to find it.
[reply]

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