use Perl

• self-import-ant? (Score:2)

  by merlyn (47)

  Not sure what you're doing there. The require is likely loading the program into the main namespace, just like you already are. The import is importing against main, from main. I bet if you remove it, it works exactly the same.

  --
  

  • Randal L. Schwartz
  • Stonehenge
• Except that it does not work... (Score:1)

  by dakkar (5832)

  Let's say you have this prog.pl:

  #!/usr/bin/perl
  
  sub do_something {
      return 42;
  }
  
  print "Running\n";

  and this test.pl:

  #!/usr/bin/perl
  
  require 'prog.pl';
  print "ok 1\n" if do_something()==42;

  Now, running test.pl produces:

  Running
  ok 1

  because the require will execute the program. So, if the program dies because @ARGV is wrong, or somesuch, your test dies as well...
• What you should do is change the program (Score:2)

  by bart (450)

  If at the top level, you check caller(), you'll find it is false if the script is run as a standalone program, and true if it's loaded as a library.
  
  Thus, do this at the top level:

  unless(caller) {
     # former top level
     print "Run as a script\n";
  } else {
     # you may drop this if you don't need it
     print "Initializing as a library file\n";
  }

  It'll work now.
  • Re: (Score:2)

    by jdavidb (1361)

    Thank you. Sounds like this advice was either present in the slides I read, and I missed it (it was middle of the night, up late hacking for work :) ), or else the presenter missed it or only mentioned it orally without including it in the slides.

    --
    J. David works really hard, has a passion for writing good software, and knows many of the world's best Perl programmers
• It's a Method! (Score:1)

  by chromatic (983)

  Besides your update, import() is a method. When you call methods as functions in Perl, you don't always get what you want.

  I think you'll have more luck checking caller() to see if someone has invoked your program directly.
• Perhaps you heard about modulinos (Score:2)

  by brian_d_foy (44)

  You write your programs as modules, where the main script is actually wrapped in a subroutine (just like the good old days of int main(void)). Now a program is just a set of subroutines and you can use it like every other library of subroutines (including testing it).
  
  I write about it in Chapter 18 of Mastering Perl [pair.com]
• Here's how I did it (Score:1)

  by Phred (5358)

  Hopefully it wasn't my slides [redhotpenguin.com] that were way off ;-) Here's how I poked at the internals of a program, including global variables. I got the idea from another post here on use Perl, and I hacked out this working program and test.

  phred@pooky ~ $ cat program.pl
  #!perl -w
  
  use strict;
  use warnings;
  
  our $var = 0;
  
  sub addition {
      my ($one, $other_one) = @_;
      my $result = $one + $other_one+$var;
      return $result;
  }
  
  sub should_die {
      die "oops";
  }
  
  1;
  
  phred@pooky ~ $ cat
  • Re: (Score:1)

    by Phred (5358)

    Oops, I forgot the output

    phred@pooky ~ $ perl foo.t
    1..3
    ok 1 - require 'program.pl';
    ok 2 - 1+1+var returns 7
    ok 3 - should_die() died