phpman > man > strictures(3pm)

NAME
    strictures - Turn on strict and make most warnings fatal

SYNOPSIS
      use strictures 2;

    is equivalent to

      use strict;
      use warnings FATAL => 'all';
      use warnings NONFATAL => qw(
        exec
        recursion
        internal
        malloc
        newline
        experimental
        deprecated
        portable
      );
      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 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 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)).

CATEGORY SELECTIONS
    strictures does not enable fatal warnings for all categories.

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

    recursion
        Infinite recursion will end up overflowing the stack eventually anyway.

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

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

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

    experimental
        Experimental features are used intentionally.

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

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

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

VERSIONS
    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;

  VERSION 2
    Equivalent to:

      use strict;
      use warnings FATAL => 'all';
      use warnings NONFATAL => qw(
        exec
        recursion
        internal
        malloc
        newline
        experimental
        deprecated
        portable
      );
      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.

  VERSION 1
    Equivalent to:

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

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

  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* 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".

SEE ALSO
    *   indirect

    *   multidimensional

    *   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 AT shadowcat.uk>

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

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

    haarg - Graham Knop (cpan:HAARG) <haarg AT 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.