strictures


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", ".svn", or ".hg" is present in the current
       directory (with the intention of only forcing extra tests on the author
       side) -- or when ".git", ".svn", or ".hg" 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 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
       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/>
       to explain this particular problem before strictures itself existed.

       As such, in my experience so far strictures' extra testing has avoided
       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".

SEE ALSO
       o   indirect

       o   multidimensional

       o   bareword::filehandles

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
       Karen Etheridge (cpan:ETHER) <ether@cpan.org>

       Mithaldu - Christian Walde (cpan:MITHALDU) <walde.christian@gmail.com>

       haarg - Graham Knop (cpan:HAARG) <haarg@haarg.org>

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 v5.18.1                      2013-12-11                   strictures(3pm)
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