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strictures(3)                        User Contributed Perl Documentation                       strictures(3)



NAME
       strictures - turn on strict and make all warnings fatal

SYNOPSIS
         use strictures 1;

       is equivalent to

         use strict;
         use warnings FATAL => 'all';

       except when called from a file which matches:

         (caller)[1] =~ /^(?:t|xt|lib|blib)/

       and when either ".git" or ".svn" is present in the current directory (with the intention of only
       forcing extra tests on the author side) -- or when ".git" or ".svn" is present two directories up
       along with "dist.ini" (which would indicate we are in a "dzil test" operation, via Dist::Zilla) -- or
       when the "PERL_STRICTURES_EXTRA" environment variable is set, in which case

         use strictures 1;

       is equivalent to

         use strict;
         use warnings FATAL => 'all';
         no indirect 'fatal';
         no multidimensional;
         no bareword::filehandles;

       Note that "PERL_STRICTURES_EXTRA" may at some point add even more tests, with only a minor version
       increase, but any changes to the effect of "use strictures" in normal mode will involve a major
       version bump.

       If any of the extra testing modules are not present, strictures will complain loudly, once, via
       "warn()", and then shut up. But you really should consider installing them, they're all great anti-footgun antifootgun
       footgun tools.

DESCRIPTION
       I've been writing the equivalent of this module at the top of my code for about a year now. I figured
       it was time to make it shorter.

       Things like the importer in "use Moose" don't help me because they turn warnings on but don't make
       them fatal -- which from my point of view is useless because I want an exception to tell me my code
       isn't warnings-clean.

       Any time I see a warning from my code, that indicates a mistake.

       Any time my code encounters a mistake, I want a crash -- not spew to STDERR and then unknown (and
       probably undesired) subsequent behaviour.

       I also want to ensure that obvious coding mistakes, like indirect object syntax (and not so obvious
       mistakes that cause things to accidentally compile as such) get caught, but not at the cost of an XS
       dependency and not at the cost of blowing things up on another machine.

       Therefore, strictures turns on additional checking, but only when it thinks it's running in a test
       file in a VCS checkout -- although if this causes undesired behaviour this can be overridden by
       setting the "PERL_STRICTURES_EXTRA" environment variable.

       If additional useful author side checks come to mind, I'll add them to the "PERL_STRICTURES_EXTRA"
       code path only -- this will result in a minor version increase (e.g.  1.000000 to 1.001000 (1.1.0) or
       similar). Any fixes only to the mechanism of this code will result in a sub-version increase (e.g.
       1.000000 to 1.000001 (1.0.1)).

       If the behaviour of "use strictures" in normal mode changes in any way, that will constitute a major
       version increase -- and the code already checks when its version is tested to ensure that

         use strictures 1;

       will continue to only introduce the current set of strictures even if 2.0 is installed.

METHODS
   import
       This method does the setup work described above in "DESCRIPTION"

   VERSION
       This method traps the "strictures->VERSION(1)" call produced by a use line with a version number on
       it and does the version check.

EXTRA TESTING RATIONALE
       Every so often, somebody complains that they're deploying via "git pull" and that they don't want
       strictures to enable itself in this case -- and that setting "PERL_STRICTURES_EXTRA" to 0 isn't
       acceptable (additional ways to disable extra testing would be welcome but the discussion never seems
       to get that far).

       In order to allow us to skip a couple of stages and get straight to a productive conversation, here's
       my current rationale for turning the extra testing on via a heuristic:

       The extra testing is all stuff that only ever blows up at compile time; this is intentional. So the
       oft-raised concern that it's different code being tested is only sort of the case -- none of the
       modules involved affect the final optree to my knowledge, so the author gets some additional compile
       time crashes which he/she then fixes, and the rest of the testing is completely valid for all
       environments.

       The point of the extra testing -- especially "no indirect" -- is to catch mistakes that newbie users
       won't even realise are mistakes without help. For example,

         foo { ... };

       where foo is an & prototyped sub that you forgot to import -- this is pernicious to track down since
       all seems fine until it gets called and you get a crash. Worse still, you can fail to have imported
       it due to a circular require, at which point you have a load order dependent bug which I've seen
       before now only show up in production due to tiny differences between the production and the
       development environment. I wrote http://shadow.cat/blog/matt-s-trout/indirect-but-still-fatal/
       <http://shadow.cat/blog/matt-s-trout/indirect-but-still-fatal/> to explain this particular problem
       before strictures itself existed.

       As such, in my experience so far strictures' extra testing has avoided production versus development
       differences, not caused them.

       Additionally, strictures' policy is very much "try and provide as much protection as possible for
       newbies -- who won't think about whether there's an option to turn on or not" -- so having only the
       environment variable is not sufficient to achieve that (I get to explain that you need to add "use
       strict" at least once a week on freenode #perl -- newbies sometimes completely skip steps because
       they don't understand that that step is important).

       I make no claims that the heuristic is perfect -- it's already been evolved significantly over time,
       especially for 1.004 where we changed things to ensure it only fires on files in your checkout
       (rather than strictures-using modules you happened to have installed, which was just silly). However,
       I hope the above clarifies why a heuristic approach is not only necessary but desirable from a point
       of view of providing new users with as much safety as possible, and will allow any future discussion
       on the subject to focus on "how do we minimise annoyance to people deploying from checkouts
       intentionally".

COMMUNITY AND SUPPORT
   IRC channel
       irc.perl.org #toolchain

       (or bug 'mst' in query on there or freenode)

   Git repository
       Gitweb is on http://git.shadowcat.co.uk/ and the clone URL is:

         git clone git://git.shadowcat.co.uk/p5sagit/strictures.git

       The web interface to the repository is at:

         http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=p5sagit/strictures.git

AUTHOR
       mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>

CONTRIBUTORS
       None required yet. Maybe this module is perfect (hahahahaha ...).

COPYRIGHT
       Copyright (c) 2010 the strictures "AUTHOR" and "CONTRIBUTORS" as listed above.

LICENSE
       This library is free software and may be distributed under the same terms as perl itself.



perl v5.16.2                                     2012-09-08                                    strictures(3)