Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things
 
PerlMonks  

New switches for perl(1)

by Aristotle (Chancellor)
on Apr 21, 2003 at 13:06 UTC ( #251986=sourcecode: print w/ replies, xml ) Need Help??

Category: Utility Scripts
Author/Contact Info /msg Aristotle
Description:

If, like me, the vast majority of oneliners you write are -n or -p ones, you'll probably have cursed at the verbosity and unwieldiness of the -e'BEGIN { $foo } s/bar/baz; END { $quux }' construct.

Hey, I thought, I can do better than that.

So I ripped apart the Getopt::Std code and based this script on it, which adds two options to Perl:

-B
This works just like -e, except it also wraps the code in a BEGIN block.
-E
This also works like -e, except it wraps the code in a END block.

Enjoy.

Update: changed hardcoded location of Perl binary to $^X in last line as per bart's suggestion.

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

my %blockname = (
    e => '%s;',
    B => '; BEGIN { %s };',
    E => '; END { %s };',
);

my @arg;

while (@ARGV && (my ($switch, $rest) = $ARGV[0] =~ /^-(.)(.*)/)) {
    if ($rest eq '-') { # early exit if --
        push @arg, @ARGV;
        last;
    }
    
    if ($switch !~ /[BEe]/) {
        push @arg, shift @ARGV;
        next;
    }
    
    shift (@ARGV);
    if (not length $rest) {
        if(@ARGV) {
            $rest = shift (@ARGV);
        }
        else {
            $! = 2; # emulate perl(1)
            die "No code specified for -$switch.";
        }
    }

    push @arg, -e => sprintf $blockname{$switch}, $rest;
}

exec { $^X } $^X, @arg;

Comment on New switches for perl(1)
Download Code
Re: New switches for perl(1)
by bart (Canon) on Apr 22, 2003 at 06:37 UTC
    You've hardcoded your path to your perl binary in the script. Maybe that's OK, because it's hardwired in the shebang line as well... but personally, I would still prefer use of the special variable $^X, anyway. In your case, it also will contain the value '/usr/bin/perl'. But it will make less problems for maintenance, for people whose perl is in another location.
    exec { $^X } $^X, @arg;
      I briefly thought about this actually. Didn't know about $^X though - I guess I should crack the cover on perlvar again sometime. :) Thanks for the suggestion, accepted.

      Makeshifts last the longest.

Back to Code Catacombs

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: sourcecode [id://251986]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others wandering the Monastery: (8)
As of 2014-09-16 10:22 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    How do you remember the number of days in each month?











    Results (5 votes), past polls