Skip to main content

If I Could Change Perl

Is there something that irritates you about Perl? One little thing you wish you could change, to make life so much easier?

For me, it's the way declarations work. Whether it's with local, our or my, you can declare a variable name, or a list of several variable names:

my ($x, $y, $z);
Of course, you can initaliaze variables as you declare them.
my $bank_balance = -999_999;
my ( $x, $y, $z ) = ( 0, 0, 0 );

But if you have a number of variables to declare, and they aren't directly related to each other, as (x, y, z) clearly are, it would be so much better to declare the variable and immediately assign a value to it on the same line, the way C, Javascript and numerous sensible langages do.

Currently, 'my', 'our' and 'local' expect a variable name, or a list of mariable names. So one possibility would be to provide an alternative form which takes a hash. Ideally, values defined in one line could be used lower down.

my {
    $sides => 3,
    $lengths => [3, 4, 5],
I suppose people will ignore this article or come out with an explanation of why I'm wrong.
All the same, what little feature would make your Perl day better?


Caleb Cushing said…
exception objects, try/catch syntax, Carp functions become syntax, and the deprecation of die (must be an object or Carp function).
Tom Legrady said…
Would be nice to have them in the language, but they do exist as modules.
Caleb Cushing said…
try/catch as modules doesn't allow me to return in the try/catch which results in me writing code to compensate. Exception modules are all over the place and there's real telling what the good ones are (unless you know the authors). Die is just a bane on the debugging dev but some people don't want to put `use Carp` because it adds a dependency. Basically modules have taken us as far as we can go here... this really needs to be language features. Modules are great but they have limits.
pmakholm said…
If the variables are not related, then don't declare them in the same statement.

I do not see any advantage with your proposed syntax over just using multiple declarations of independent variables.

As I see it this is also how it is done in C.
abraxxa said…
This should work, although I see no benefit over declaring each var on its own line:

my ( $sides, $lengths ) = ( 3, [3, 4, 5] );

Popular posts from this blog

Creating Perl5 Objects with Moxie

Having in the previous article prepared data types for car suits and card ranks, I can now combine them to provide a playing card class, using Stevan Little's Moxie module (version 0.04, so definitely early days.) The goal is to provide an object-oriented paradigm to the Perl 5 programming language which is more sophisticated, more powerful and less verbose than manually bless()-ing hashes. To achieve that goal it needs to be faster and light-weight compared to Moose. Currently, and and are add-on modules, but eventually, when they are more complete, when the wrinkles have been ironed out, and when they have gained acceptance and a community of users, they might be merged into the Perl core.

One significant feature of Moxie is that it reduces boilerplate code. You don't have to specify warnigns or strict. As well, the features or the perl you are using are enabled, among them say, state, signatures, and post_deref.
A Simple Moxie Class package Card { …

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<. So I was delighted to recently see an announcement of the module Moxie, and decided to try implementing a card game.

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; …

Adventures in Autovivification

Having recently started a new job, I was exposed to old code with multi-step tests against autovivification in multi-level hashes. You get used to the code you have seen, but in a new environment it‘s irritating and jarring.
Moose does not generally have the problem, first because class structure is pre-declared, because values are accessed using accessor functions rather than directly, and because responsibility is delegated down to attributes, avoiding long chains. On the other hand, Moose has it's own overhead, so hand-rolled objects, and bare structures still have their use.
If you don‘t protect against autovivification, then mis-spelling a key, or referencing keys which haven‘t been instantiated in this instance, causes those keys to instantly come into existence.
#!/usr/bin/perl use warnings; use strict; use Data::Dump 'dump'; use 5.024; my $var = {key1 => {key2 => {key3 => 'a'}}}; say dump $var; if ( $var->{key1}{key2}{key3b}[13]{foob…