Commit | Line | Data |
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1 | package Symbol; |
2 | |
3 | =head1 NAME |
4 | |
5 | Symbol - manipulate Perl symbols and their names |
6 | |
7 | =head1 SYNOPSIS |
8 | |
9 | use Symbol; |
10 | |
11 | $sym = gensym; |
12 | open($sym, "filename"); |
13 | $_ = <$sym>; |
14 | # etc. |
15 | |
16 | ungensym $sym; # no effect |
17 | |
18 | print qualify("x"), "\n"; # "Test::x" |
19 | print qualify("x", "FOO"), "\n" # "FOO::x" |
20 | print qualify("BAR::x"), "\n"; # "BAR::x" |
21 | print qualify("BAR::x", "FOO"), "\n"; # "BAR::x" |
22 | print qualify("STDOUT", "FOO"), "\n"; # "main::STDOUT" (global) |
23 | print qualify(\*x), "\n"; # returns \*x |
24 | print qualify(\*x, "FOO"), "\n"; # returns \*x |
25 | |
26 | =head1 DESCRIPTION |
27 | |
28 | C<Symbol::gensym> creates an anonymous glob and returns a reference |
29 | to it. Such a glob reference can be used as a file or directory |
30 | handle. |
31 | |
32 | For backward compatibility with older implementations that didn't |
33 | support anonymous globs, C<Symbol::ungensym> is also provided. |
34 | But it doesn't do anything. |
35 | |
36 | C<Symbol::qualify> turns unqualified symbol names into qualified |
37 | variable names (e.g. "myvar" -> "MyPackage::myvar"). If it is given a |
38 | second parameter, C<qualify> uses it as the default package; |
39 | otherwise, it uses the package of its caller. Regardless, global |
40 | variable names (e.g. "STDOUT", "ENV", "SIG") are always qualfied with |
41 | "main::". |
42 | |
43 | Qualification applies only to symbol names (strings). References are |
44 | left unchanged under the assumption that they are glob references, |
45 | which are qualified by their nature. |
46 | |
47 | =cut |
48 | |
3dc8e7ab |
49 | BEGIN { require 5.002; } |
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50 | |
51 | require Exporter; |
52 | @ISA = qw(Exporter); |
53 | |
54 | @EXPORT = qw(gensym ungensym qualify); |
55 | |
56 | my $genpkg = "Symbol::"; |
57 | my $genseq = 0; |
58 | |
59 | my %global; |
60 | while (<DATA>) { |
61 | chomp; |
62 | $global{$_} = 1; |
63 | } |
3c4fed68 |
64 | close DATA; |
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65 | |
66 | sub gensym () { |
67 | my $name = "GEN" . $genseq++; |
68 | local *{$genpkg . $name}; |
69 | \delete ${$genpkg}{$name}; |
70 | } |
71 | |
72 | sub ungensym ($) {} |
73 | |
74 | sub qualify ($;$) { |
75 | my ($name) = @_; |
49da0595 |
76 | if (!ref($name) && index($name, '::') == -1 && index($name, "'") == -1) { |
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77 | my $pkg; |
78 | # Global names: special character, "^x", or other. |
79 | if ($name =~ /^([^a-z])|(\^[a-z])$/i || $global{$name}) { |
80 | $pkg = "main"; |
81 | } |
82 | else { |
83 | $pkg = (@_ > 1) ? $_[1] : caller; |
84 | } |
85 | $name = $pkg . "::" . $name; |
86 | } |
87 | $name; |
88 | } |
89 | |
90 | 1; |
91 | |
92 | __DATA__ |
93 | ARGV |
94 | ARGVOUT |
95 | ENV |
96 | INC |
97 | SIG |
98 | STDERR |
99 | STDIN |
100 | STDOUT |