Skip to main content

Learning Perl5i

I've been looking at the module perl5i, which puts a sideways twist on Perl, eliminating tons of boring boilerplate, and introduce many conveniences. In this case, the i eliminates complexity.

Installing perl5i installs a number of other modules as well, on the other hand life becomes better once they are installed.

If you don't have cpanm or one of the other improved CPAN installers, the simplest way is to install perl5i and its friends using the command

     sudo cpan perl5i

You may need to type in yes to have cpan  install dependencies. Some modules are needed only temporarily during installation, and you are asked whether you want them permanently installed. Perl modules don't take up very much space, so I always go for it. Installation is a bit different on Windows or Linux machines, but you can figure it out, you're a mighty Perl programmer!

One consideration is that major versions of perl5i may change in drastic ways. But you don't include perl5i; what you specify is perl5i::2. The newest module includes perl5i::0 and perl5i::1 as well, so old code is supported until you are ready to upgrade them.

The immediate benefit is that you no longer have to enable strictness. perl5i automatically provides

     use warnings;
  use strict;

So it costs you 14 characters to type

    use perl5i::2;

and straight off the bat it saves you 24 characters ....profit!


Oh, and it automatically activates features say, state and switch.


But wait! There's more! Not only does it slice and dice, it also julienes!

Well, no cutting anything in any shape ... but perl5i DOES provide autodie. If your open() doesn't work, the program dies; if the close() doesn't work, the program dies; if print() or a system() call or unlink() don't work, the program dies with an exception that turns into a string if you don't handle it.

Having a program die is an effective way to trigger in-house failure detection systems, such as Nagios. So simply doing the things you want, without checking return values, becomes a viable way to write a secure program that detects problems. If you need to catch and handle problems, perl5i provides Try::Tiny. There are other attempts at exception handling; any of them would be clearer than using eval. Try::Tiny is small, it does the job, and the intent is clear.

    try {
        open my $h, '<', '/does/not/exist';
    } 
    catch {
        say "the open() died with message $_";
    };

You can also add a finally block, to perform things that need to happen regardless of success or failure. The single weakness is that try is a statement, not a block, so it needs a semi-colon

So that's a major from installing perl5i, and we've barely gotten started.

Comments

Popular posts from this blog

Perl5, Moxie and Enumurated Data Types

Moxie - a new object system for Perl5 Stevan Little created the Moose multiverse to upgrade the Perl 5 programming language's object-oriented system more in line with the wonderfull world of Perl 6. Unfortunately, it's grown into a bloated giant, which has inspired light-weight alternatives Moos, Moo, Mo, and others. Now he's trying to create a modern, efficient OO system that can become built into the language. I've seen a few of his presentations at YAPC (Yet Another Perl Conference, now known as TPC, The Perl Conference), among them ‎p5 mop final final v5 this is the last one i promise tar gz While the package provides some POD documentation about the main module, Moxie, it doesn't actually explain the enum package, Moxie::Enum. But delving into the tests directory reveals its secrets. Creating an Enum package Ranks { use Moxie::Enum; enum by_ARRAY => qw( unused 2 3 4 5 6 7 8 9 10 J Q K A ); enum by_HASH => { 2 => 2, 3 =...

Implementing the Game with Perl & Moxie

I've been creating classes relating to playing cards using the new Moxie module for the Perl programming language. The objective is to implement the card game Go Fish! as specified at Rosetta Code . The Outside-In View An actual program file should be simple; all the real code should be in testable modules. In this case, play_go_fish.pl takes this to an extreme. #!/usr/bin/env perl use warnings; use strict; use 5.026; use lib '.'; use Game; Game->new()->play(); As of Perl 5.26, the current directory is not automatically part of @INC, the search path for modules, so it is necessary to include it manually. That makes it possible to load the Game module, to instantiate an instance, and play a game. package Game; use Moxie; use lib '.'; use Deck; use Computer; use Human; use Const::Fast; extends 'Moxie::Object'; const my @PLAYERS => qw( human computer ); const my $INITIAL_DEAL_COUNT => 9; A Game.pm object begins like most ot...

AI crap at 100 words a minute

I requested an AI to  create an astable multivibrator that can oscillate at 100KHz with a 50% duty cycle. Of course, this isn't an essay topic, it's a (trivial) electronic circuit. But it set out to provide the required number of words without actually saying anything useful. Here's what came out ... Note the reference to an article from 1968, long before any modern technology. In particular, getting through several paragraphs about oscillators without mentioning the 55 timer ic is unimaginable.