X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fstrict.pm;h=8afb9a37921c13127577a5cd8e129517b58bc46d;hb=847a5fae45dac396d0f9e1bb61d5b4ff9d94cdcd;hp=adaf47c720269081d9e07ead17988a8d40249e7e;hpb=a0d0e21ea6ea90a22318550944fe6cb09ae10cda;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/strict.pm b/lib/strict.pm index adaf47c..8afb9a3 100644 --- a/lib/strict.pm +++ b/lib/strict.pm @@ -1,12 +1,106 @@ package strict; +=head1 NAME + +strict - Perl pragma to restrict unsafe constructs + +=head1 SYNOPSIS + + use strict; + + use strict "vars"; + use strict "refs"; + use strict "subs"; + + use strict; + no strict "vars"; + +=head1 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". + +=over 6 + +=item C + +This generates a runtime error if you +use symbolic references (see L). + + 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 C would not break under stricture. + + +=item C + +This generates a compile-time error if you access a variable that wasn't +declared via "our" or C, +localized via C, 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 L and +L. + + 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. + +=item C + +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 "=E" symbol. + + + use strict 'subs'; + $SIG{PIPE} = Plumber; # blows up + $SIG{PIPE} = "Plumber"; # just fine: bareword in curlies always ok + $SIG{PIPE} = \&Plumber; # preferred form + + + +=back + +See L. + + +=cut + +$strict::VERSION = "1.01"; + +my %bitmask = ( +refs => 0x00000002, +subs => 0x00000200, +vars => 0x00000400 +); + sub bits { my $bits = 0; - foreach $sememe (@_) { - $bits |= 0x00000002 if $sememe eq 'refs'; - $bits |= 0x00000200 if $sememe eq 'subs'; - $bits |= 0x00000400 if $sememe eq 'vars'; - } + foreach my $s (@_){ $bits |= $bitmask{$s} || 0; }; $bits; }