ActiveState!

ActivePerl Documentation
Table of Contents

(Usage Statistics)
(about this ver)


* Getting Started
    * Welcome To ActivePerl
    * Release Notes
    * Readme
    * ActivePerl Change Log
* Install Notes
    * Linux
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* ActivePerl Components
    * Overview
    * PPM
    * Windows Specifics
       * OLE Browser
       * PerlScript
       * Perl for ISAPI
       * PerlEZ
* ActivePerl FAQ
    * Introduction
    * Availability & Install
    * Using PPM
    * Docs & Support
    * Windows Specifics
       * Perl for ISAPI
       * Windows 9X/NT/2000
       * Quirks
       * Web Server Config
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       * Using OLE with Perl
* Windows Scripting
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 strict - Perl pragma to restrict unsafe constructs


NAME

strict - Perl pragma to restrict unsafe constructs


SUPPORTED PLATFORMS

  • Linux
  • Solaris
  • Windows

SYNOPSIS

    use strict;
    use strict "vars";
    use strict "refs";
    use strict "subs";
    use strict;
    no strict "vars";


DESCRIPTION

If no import list is supplied, all possible restrictions are assumed. (This is the safest mode to operate in, but is sometimes too strict for casual programming.) Currently, there are three possible things to be strict about: ``subs'', ``vars'', and ``refs''.

strict refs
This generates a runtime error if you use symbolic references (see the perlref manpage).
    use strict 'refs';
    $ref = \$foo;
    print $$ref;        # ok
    $ref = "foo";
    print $$ref;        # runtime error; normally ok
    $file = "STDOUT";
    print $file "Hi!";  # error; note: no comma after $file

strict vars
This generates a compile-time error if you access a variable that wasn't declared via ``our'' or use vars, localized via my(), or wasn't fully qualified. Because this is to avoid variable suicide problems and subtle dynamic scoping issues, a merely local() variable isn't good enough. See my in the perlfunc manpage and local in the perlfunc manpage.
    use strict 'vars';
    $X::foo = 1;         # ok, fully qualified
    my $foo = 10;        # ok, my() var
    local $foo = 9;      # blows up
    package Cinna;
    our $bar;                   # Declares $bar in current package
    $bar = 'HgS';               # ok, global declared via pragma

The local() generated a compile-time error because you just touched a global name without fully qualifying it.

Because of their special use by sort(), the variables $a and $b are exempted from this check.

strict subs
This disables the poetry optimization, generating a compile-time error if you try to use a bareword identifier that's not a subroutine, unless it appears in curly braces or on the left hand side of the ``=>'' symbol.
    use strict 'subs';
    $SIG{PIPE} = Plumber;       # blows up
    $SIG{PIPE} = "Plumber";     # just fine: bareword in curlies always ok
    $SIG{PIPE} = \&Plumber;     # preferred form

See Pragmatic Modules in the perlmodlib manpage.

 strict - Perl pragma to restrict unsafe constructs