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

       strictures - Turn on strict and make most warnings fatal

         use strictures 2;

       is equivalent to

         use strict;
         use warnings FATAL => 'all';
         use warnings NONFATAL => qw(
         no warnings 'once';

       except when called from a file which matches:

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

       and when either ".git", ".svn", ".hg", or ".bzr" is present in the
       current directory (with the intention of only forcing extra tests on
       the author side) -- or when ".git", ".svn", ".hg", or ".bzr" 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 it
       also does the equivalent of

         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

       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.

       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-

       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)).

       strictures does not enable fatal warnings for all categories.

           Includes a warning that can cause your program to continue running
           unintentionally after an internal fork.  Not safe to fatalize.

           Infinite recursion will end up overflowing the stack eventually

           Triggers deep within perl, in places that are not safe to trap.

           Triggers deep within perl, in places that are not safe to trap.

           Includes a warning for using stat on a valid but suspect filename,
           ending in a newline.

           Experimental features are used intentionally.

           Deprecations will inherently be added to in the future in
           unexpected ways, so making them fatal won't be reliable.

           Doesn't indicate an actual problem with the program, only that it
           may not behave properly if run on a different machine.

           Can't be fatalized.  Also triggers very inconsistently, so we just
           disable it.

       Depending on the version of strictures requested, different warnings
       will be enabled.  If no specific version is requested, the current
       version's behavior will be used.  Versions can be requested using
       perl's standard mechanism:

         use strictures 2;

       Or, by passing in a "version" option:

         use strictures version => 2;

       Equivalent to:

         use strict;
         use warnings FATAL => 'all';
         use warnings NONFATAL => qw(
         no warnings 'once';

         # and if in dev mode:
         no indirect 'fatal';
         no multidimensional;
         no bareword::filehandles;

       Additionally, any warnings created by modules using warnings::register
       or "warnings::register_categories()" will not be fatalized.

       Equivalent to:

         use strict;
         use warnings FATAL => 'all';
         # and if in dev mode:
         no indirect 'fatal';
         no multidimensional;
         no bareword::filehandles;

       This method does the setup work described above in "DESCRIPTION".
       Optionally accepts a "version" option to request a specific version's

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

       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 <>
       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".

       o   indirect

       o   multidimensional

       o   bareword::filehandles

   IRC channel #toolchain

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

   Git repository
       Gitweb is on and the clone URL is:

         git clone git://

       The web interface to the repository is at:

       mst - Matt S. Trout (cpan:MSTROUT) <>

       Karen Etheridge (cpan:ETHER) <>

       Mithaldu - Christian Walde (cpan:MITHALDU) <>

       haarg - Graham Knop (cpan:HAARG) <>

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

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

perl v5.28.1                      2019-07-15                   strictures(3pm)
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