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vars(3pm) [centos man page]

vars(3pm)						 Perl Programmers Reference Guide						 vars(3pm)

NAME
vars - Perl pragma to predeclare global variable names (obsolete) SYNOPSIS
use vars qw($frob @mung %seen); DESCRIPTION
NOTE: For variables in the current package, the functionality provided by this pragma has been superseded by "our" declarations, available in Perl v5.6.0 or later. See "our" in perlfunc. This will predeclare all the variables whose names are in the list, allowing you to use them under "use strict", and disabling any typo warnings. Unlike pragmas that affect the $^H hints variable, the "use vars" and "use subs" declarations are not BLOCK-scoped. They are thus effective for the entire file in which they appear. You may not rescind such declarations with "no vars" or "no subs". Packages such as the AutoLoader and SelfLoader that delay loading of subroutines within packages can create problems with package lexicals defined using "my()". While the vars pragma cannot duplicate the effect of package lexicals (total transparency outside of the package), it can act as an acceptable substitute by pre-declaring global symbols, ensuring their availability to the later-loaded routines. See "Pragmatic Modules" in perlmodlib. perl v5.16.3 2013-03-04 vars(3pm)

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strict(3pm)						 Perl Programmers Reference Guide					       strict(3pm)

NAME
strict - Perl pragma to restrict unsafe constructs 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 perlref). 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 There is one exception to this rule: $bar = &{'foo'}; &$bar; is allowed so that "goto &$AUTOLOAD" would not break under stricture. "strict vars" This generates a compile-time error if you access a variable that was neither explicitly declared (using any of "my", "our", "state", or "use vars") nor 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 perlfunc, "our" in perlfunc, "state" in perlfunc, "local" in perlfunc, and vars. use strict 'vars'; $X::foo = 1; # ok, fully qualified my $foo = 10; # ok, my() var local $baz = 9; # blows up, $baz not declared before 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 is a simple identifier (no colons) and that 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: quoted string is always ok $SIG{PIPE} = &Plumber; # preferred form See "Pragmatic Modules" in perlmodlib. HISTORY
"strict 'subs'", with Perl 5.6.1, erroneously permitted to use an unquoted compound identifier (e.g. "Foo::Bar") as a hash key (before "=>" or inside curlies), but without forcing it always to a literal string. Starting with Perl 5.8.1 strict is strict about its restrictions: if unknown restrictions are used, the strict pragma will abort with Unknown 'strict' tag(s) '...' As of version 1.04 (Perl 5.10), strict verifies that it is used as "strict" to avoid the dreaded Strict trap on case insensitive file systems. perl v5.18.2 2014-01-06 strict(3pm)
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