Commit | Line | Data |
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c07a80fd | 1 | package vars; |
2 | ||
fb73857a | 3 | require 5.002; |
4 | ||
5 | # The following require can't be removed during maintenance | |
6 | # releases, sadly, because of the risk of buggy code that does | |
7 | # require Carp; Carp::croak "..."; without brackets dying | |
8 | # if Carp hasn't been loaded in earlier compile time. :-( | |
9 | # We'll let those bugs get found on the development track. | |
10 | require Carp if $] < 5.00450; | |
11 | ||
12 | sub import { | |
13 | my $callpack = caller; | |
14 | my ($pack, @imports, $sym, $ch) = @_; | |
15 | foreach $sym (@imports) { | |
fb73857a | 16 | ($ch, $sym) = unpack('a1a*', $sym); |
014aafb8 | 17 | if ($sym =~ tr/A-Za-z_0-9//c) { |
15313f9c TP |
18 | # time for a more-detailed check-up |
19 | if ($sym =~ /::/) { | |
20 | require Carp; | |
21 | Carp::croak("Can't declare another package's variables"); | |
22 | } elsif ($sym =~ /^\w+[[{].*[]}]$/) { | |
23 | require Carp; | |
24 | Carp::croak("Can't declare individual elements of hash or array"); | |
25 | } elsif ($^W and length($sym) == 1 and $sym !~ tr/a-zA-Z//) { | |
26 | require Carp; | |
27 | Carp::carp("No need to declare built-in vars"); | |
28 | } | |
29 | } | |
fb73857a | 30 | *{"${callpack}::$sym"} = |
31 | ( $ch eq "\$" ? \$ {"${callpack}::$sym"} | |
32 | : $ch eq "\@" ? \@ {"${callpack}::$sym"} | |
33 | : $ch eq "\%" ? \% {"${callpack}::$sym"} | |
34 | : $ch eq "\*" ? \* {"${callpack}::$sym"} | |
35 | : $ch eq "\&" ? \& {"${callpack}::$sym"} | |
36 | : do { | |
37 | require Carp; | |
15313f9c | 38 | Carp::croak("'$ch$sym' is not a valid variable name"); |
fb73857a | 39 | }); |
40 | } | |
41 | }; | |
42 | ||
43 | 1; | |
44 | __END__ | |
45 | ||
c07a80fd | 46 | =head1 NAME |
47 | ||
48 | vars - Perl pragma to predeclare global variable names | |
49 | ||
50 | =head1 SYNOPSIS | |
51 | ||
52 | use vars qw($frob @mung %seen); | |
53 | ||
54 | =head1 DESCRIPTION | |
55 | ||
56 | This will predeclare all the variables whose names are | |
57 | in the list, allowing you to use them under "use strict", and | |
58 | disabling any typo warnings. | |
59 | ||
55497cff | 60 | Unlike pragmas that affect the C<$^H> hints variable, the C<use vars> and |
61 | C<use subs> declarations are not BLOCK-scoped. They are thus effective | |
62 | for the entire file in which they appear. You may not rescind such | |
63 | declarations with C<no vars> or C<no subs>. | |
64 | ||
7a2e2cd6 | 65 | Packages such as the B<AutoLoader> and B<SelfLoader> that delay |
66 | loading of subroutines within packages can create problems with | |
67 | package lexicals defined using C<my()>. While the B<vars> pragma | |
68 | cannot duplicate the effect of package lexicals (total transparency | |
69 | outside of the package), it can act as an acceptable substitute by | |
70 | pre-declaring global symbols, ensuring their availability to the | |
71 | later-loaded routines. | |
c6f23971 | 72 | |
ee580363 | 73 | See L<perlmodlib/Pragmatic Modules>. |
c07a80fd | 74 | |
75 | =cut |