Module/script all in one

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

I've asked a similar question to this one before, but now I'm stuck at another junction and need some wisdom. What I'm trying to do is have a Perl module that is also usable standalone. Things are working just fine, except when it comes to passing arguments into the script. First, a little code:

#!/bin/sh

eval "exec /usr/bin/perl -I`dirname $0` -M`basename $0 .pm` -e main --
+ $@ "
    if $running_under_some_shell;

sub main {
    for my $arg (@ARGV){
    print "=>$arg<=\n";
    }
}

1;
[download]

When I run this script with arguments like "this is" "a test", I get

=>this is a test<=

when I want to get

=>this is<=
=>a test<=

I'm looking for any suggestions. I've found ways of making the shell handle things correctly, but Perl doesn't like any of the incantations that I've tried.

Comment on Module/script all in one Download Code

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Re: Module/script all in one by TomDLux (Vicar) on Jan 08, 2004 at 23:21 UTC
You've got the right idea ... outside quotes, $* and $@ are the same, but within quotes, "$*" produces one argument, while "$@" produces $# arguments. (See my quick shell tutorial. However, you have an eval & an exec; the exec gets two arguments, but combines them into one while invoking Perl. But who cares about shell? This is Perl! In your module: `if ( $0 eq __FILE__ ) { # Code to run when the module IS the program }` [download] -- `TTTATCGGTCGTTATATAGATGTTTGCA`	[reply] [d/l]
•Re: Module/script all in one by merlyn (Sage) on Jan 08, 2004 at 23:16 UTC
You need to quote your $@, as in: `eval " ... \"$@\""` [download] -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply] [d/l]
Re: Module/script all in one by ysth (Canon) on Jan 09, 2004 at 05:24 UTC
The usual way to have a module work as a script is to do something like: `if (defined caller) { print "used as a module"; } else { print "used as a script: @ARGV"; main() }` [download] Is there more that you are trying to accomplish than that?	[reply] [d/l]
Re: Module/script all in one by bschmer (Friar) on Jan 09, 2004 at 12:00 UTC
Thanks all. I guess I was a little too engrained with the shell eval exec from my Camel book to think about a pure Perl solution to the problem. Shame on me! :-(	[reply]