X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fstrict.pm;h=8492e933fd649bb3cc4c91188bb50269b3ba12fd;hb=9d17b0a6244cecb9ba7d42c6a1a882fd933f6f45;hp=adaf47c720269081d9e07ead17988a8d40249e7e;hpb=a0d0e21ea6ea90a22318550944fe6cb09ae10cda;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/strict.pm b/lib/strict.pm index adaf47c..8492e93 100644 --- a/lib/strict.pm +++ b/lib/strict.pm @@ -1,11 +1,84 @@ 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 + +=item C + +This generates a compile-time error if you access a variable that wasn't +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 + +The local() generated a compile-time error because you just touched a global +name without fully qualifying it. + +=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 + sub bits { my $bits = 0; + my $sememe; foreach $sememe (@_) { - $bits |= 0x00000002 if $sememe eq 'refs'; - $bits |= 0x00000200 if $sememe eq 'subs'; - $bits |= 0x00000400 if $sememe eq 'vars'; + $bits |= 0x00000002, next if $sememe eq 'refs'; + $bits |= 0x00000200, next if $sememe eq 'subs'; + $bits |= 0x00000400, next if $sememe eq 'vars'; } $bits; }