NAME

common::sense - save a tree AND a kitten, use common::sense!

SYNOPSIS

 use common::sense;

 # roughly the same as, with much lower memory usage:
 #
 # use strict qw(vars subs);
 # use feature qw(say state switch);
 # no warnings;

DESCRIPTION

This module implements some sane defaults for Perl programs, as defined by two typical (or not so typical - use your common sense) specimens of Perl coders.

no warnings

The dreaded warnings. Even worse, the horribly dreaded -w switch. Even though we don't care if other people use warnings (and certainly there are useful ones), a lot of warnings simply go against the spirit of Perl, most prominently, the warnings related to undef. There is nothing wrong with undef: it has well-defined semantics, it is useful, and spitting out warnings you never asked for is just evil.

So every module needs no warnings to avoid somebody accidentally using -w and forcing his bad standards on our code. No will do.

Funnily enough, perllexwarn explicitly mentions -w (and not in a favourable way), but standard utilities, such as prove, or MakeMaker when running make test enable them blindly.

use strict qw(subs vars)

Using use strict is definitely common sense, but use strict 'refs' definitely overshoots it's usefulness. After almost two decades of Perl hacking, we decided that it does more harm than being useful. Specifically, constructs like these:

   @{ $var->[0] }

Must be written like this (or similarly), when use strict 'refs' is in scope, and $var can legally be undef:

   @{ $var->[0] || [] }

This is annoying, and doesn't shield against obvious mistakes such as using "", so one would even have to write:

   @{ defined $var->[0] ? $var->[0] :  [] }

... which nobody with a bit of common sense would consider writing. Curiously enough, sometimes, perl is not so strict, as this works even with use strict in scope:

   for (@{ $var->[0] }) { ...

If that isnt hipocrasy! And all that from a mere program!

use feature qw(say state given)

We found it annoying that we always have to enable extra features. If something breaks because it didn't anticipate future changes, so be it. 5.10 broke almost all our XS modules and nobody cared either - and few modules that are no longer maintained work with newer versions of Perl, regardless of use feature.

If your code isn't alive, it's dead, jim.

much less memory

Just using all those pragmas together waste <blink>776 kilobytes</blink> of precious memory in my perl, for every single perl process using our code, which on our machines, is a lot. In comparison, this module only uses four kilobytes (I even had to write it out so it looks like more) of memory on the same platform.

The money/time/effort/electricity invested in these gigabytes (probably petabytes globally!) of wasted memory could easily save 42 trees, and a kitten!

THERE IS NO 'no common::sense'!!!! !!!! !!

This module doesn't offer an unimport. First of all, it wastes even more memory, second, and more importantly, who with even a bit of common sense would want no common sense?

STABILITY AND FUTURE VERSIONS

Future versions might change just about everything in this module. We might test our modules and upload new ones working with newer versions of this module, and leave you standing in the rain because we didn't tell you.

Most likely, we will pick a few useful warnings, instead of just disabling all of them. And maybe we will load some nifty modules that try to emulate say or so with perls older than 5.10 (this module, of course, should work with older perl versions - supporting 5.8 for example is just common sense at this time. Maybe not in the future, but of course you can trust our common sense).

AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

 Robin Redeker, "<elmex at ta-sa.org>".