I have tried creating a .pl file and the keyword "package" throws errors. I have tried creating a .pm file, then putting main code (even "print 'Hello World', before the "1;", and this throws different errors.

That makes no sense. If it works in the .pm, it'll work in the .pl. Another error must have been introduced. (It sounds like a runaway quote or a runaway block to me.)

package AverageJoe;

sub get_name { ${shift(@_)} }


package tom;

our @ISA = 'AverageJoe';

sub new {
   my $class = shift;
   my $text = "This is tom";
   return bless(\$text, $class);
}


package dick;

our @ISA = 'AverageJoe';

sub new {
   my $class = shift;
   my $text = "This is dick";
   return bless(\$text, $class);
}


package main; # Not mod_perl safe.

my $tom  = tom->new();
my $dick = dick->new();

{
   print $tom->get_name(), $/;
   print $dick->get_name(), $/;
}
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I had to make changes since 1) you weren't blessing a reference, and 2) you used $class without declaring or initializing it.

All you need to do is define the main space with package main; ... you can see an example of that here: XML::Simple + Class::MethodMaker.

Are you sure, however, that you really want to bless scalars like that? You need to bless the reference, not the scalar itself. Perhaps you meant something like this instead:

    my $self = {
        message => "This is dick",
    };
    bless ($self, $class);
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L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

bless(\$text, $class); is blessing a reference - and because bless returns the blessed value as well as acting directly upon it, the subroutine *does* return a blessed reference. See for example:

my $foo = "bar";
print bless \$foo, "Test";
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Update: Apologies to jeffa, I got confused and was reading the wrong code when replying. The OP is indeed trying to bless a non-ref scalar, which would lead to an error: Can't bless non-reference value

/J\

package MyPackage;

# if invoked from the command line, call run() with
# command-line input

__PACKAGE__->run( @ARGV ) unless caller();
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I have tried creating a .pl file and the keyword "package" throws errors. I have tried creating a .pm file, then putting main code (even "print 'Hello World', before the "1;", and this throws different errors.

• Do you have the access to distribute a custom rpm for this script? That way you could package whataver you want, and it's easy to make sure all the servers have the same version.
• Alternatively, take a look at PAR.
• Alternatively, you could just dump a tarball over.. would be executed remote with a series of commands like (untested--verify the tar syntax):

  scp foo.tar.gz user@host:/tmp
  ssh user@host "rm -rf /tmp/foo/"
  ssh user@host "tar cvfz /tmp/foo.tar.gz -C /tmp"
  ssh user@host "perl -I/tmp/foo/modules /tmp/foo/bar.pl"
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• Alternatively, have your script use LWP (if avail) or wget or lynx or curl or scp to suck down a tarball of deps/tools/utils it needs from a central server of yours.

Those are all some good thoughts, and I have even thought of writing the utility to run from a central location and use Net::SSH::Perl to do all the checks.

But my boss wants a single script that can be used to "sanity-check" a new system. This includes basic stuff like permissions on directories, mount points, etc., and more complex stuff like SSH keys.

It is a utility script that simply prints out a report of problems found. You delete it after you fix all the issues.

package tom;

sub new {
my $self = "This is tom";
bless ($self, $class);
}
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I have tried creating a .pl file and the keyword "package" throws errors.

That's very wrong. You should only bless references. This piece of code here is bound to fail.

Apologies. Of course my production code does something like this:

my $self = {
    user_name  => 'fubar',
    num_days   => 0,
};

bless ($self, $class);
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I threw the tom/dick/harry example together from memory. I wanted to emphasize that I was defining 3 classes in the same file - something that other OO languages do not like.

If it works in the .pm, it'll work in the .pl. Another error must have been introduced.

Ikegami - I think you got it - but with one exception:

You have to include shebang (#!/usr/bin/perl) at the top of a .pl, but not at the top of a .pm file.

I took my working .pm file and tried to get it to work as a .pl and it threw errors. But I did not notice the error messages were BASH error messages instead of Perl messages. (duh)

I put shebang at the top of the script - and now it actually works. Thanks Monks!

If it works in the .pm, it'll work in the .pl. Another error must have been introduced. Ikegami - I think you got it - but with one exception: You have to include shebang (#!/usr/bin/perl) at the top of a .pl, but not at the top of a .pm file.

Just to nitpick a tad, the shebang has nothing to do with the difference between a ".pl" and a ".pm". Perl sees no difference between files, whatever their extension happens to be. The only practical difference is that 'use' and 'require' will append a .pm to the package name you pass them. In any case, anything involving a shebang has to do with your shell/kernel.

I was just wandering around this place and read How a script becomes a module by brian_d_foy. It walks through exactly what you want to do. Start with script, change code, make code an internal to the script module ...

If you prefer the script code at the bottom, put "package main;" after the package code, to flip back to the main package, and you don't need to end the file with 1;

If you want more specific answers, please explain *which* errors you got while putting prints in (and give the exact code you tried, or a simplified version thereof).

C.

What is the correct syntax to create tom/dick/harry objects all in a single .pl file and then use them?

Being Perl there is no "correct" way - TIMTOWTDI and all that :-) That said I tend to always write inline classes like this:

{   package Foo;
    sub new { bless {}, shift }
    # ... other methods
}

{   package Bar;
    use base 'Foo';
    # Bar specific methods
}
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Sticking each package in its own { block } means I don't have to worry about lexical variables leaking between packages, and using use base rather than assigning to @ISA directly means I don't have to add extra use BaseClass lines if I decide to move it to a separate file.

$ echo 'package Tom;' > foo.pl

$ chmod u+x foo.pl

$ ./foo.pl              
package: not found
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$ ./foo.pl 2>&1 | splain
package: not found (#1)
    (A) You've accidentally run your script through the
    Bourne shell instead of Perl.  Check the #! line, or
    manually feed your script into Perl yourself.
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Your mistake in posting was to say "my code looks something like this, it gives some errors" and then go into a long tangent about what you THINK might be causing the errors. Much better is to say "here's the exact code, here is what I expected it to do, and here is the exact error I got." Smart Questions HOWTO.

(The mystery of how somebody who doesn't understand that #! is parsed by the shell got a job adminning 800 Linux boxes is left as an exercise to the reader.)

The mystery of how somebody who doesn't understand that #! is parsed by the shell got a job adminning 800 Linux boxes is left as an exercise to the reader.

What mystery? That's the norm, in my experience.