Commit | Line | Data |
---|---|---|
c07a80fd | 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 | ||
b42fedfb CS |
26 | use strict refs; |
27 | print { qualify_to_ref $fh } "foo!\n"; | |
28 | $ref = qualify_to_ref $name, $pkg; | |
29 | ||
1ee082b7 GS |
30 | use Symbol qw(delete_package); |
31 | delete_package('Foo::Bar'); | |
32 | print "deleted\n" unless exists $Foo::{'Bar::'}; | |
33 | ||
34 | ||
c07a80fd | 35 | =head1 DESCRIPTION |
36 | ||
37 | C<Symbol::gensym> creates an anonymous glob and returns a reference | |
38 | to it. Such a glob reference can be used as a file or directory | |
39 | handle. | |
40 | ||
41 | For backward compatibility with older implementations that didn't | |
42 | support anonymous globs, C<Symbol::ungensym> is also provided. | |
43 | But it doesn't do anything. | |
44 | ||
45 | C<Symbol::qualify> turns unqualified symbol names into qualified | |
7c584b33 | 46 | variable names (e.g. "myvar" -E<gt> "MyPackage::myvar"). If it is given a |
c07a80fd | 47 | second parameter, C<qualify> uses it as the default package; |
48 | otherwise, it uses the package of its caller. Regardless, global | |
f610777f | 49 | variable names (e.g. "STDOUT", "ENV", "SIG") are always qualified with |
c07a80fd | 50 | "main::". |
51 | ||
52 | Qualification applies only to symbol names (strings). References are | |
53 | left unchanged under the assumption that they are glob references, | |
54 | which are qualified by their nature. | |
55 | ||
b42fedfb CS |
56 | C<Symbol::qualify_to_ref> is just like C<Symbol::qualify> except that it |
57 | returns a glob ref rather than a symbol name, so you can use the result | |
58 | even if C<use strict 'refs'> is in effect. | |
59 | ||
1ee082b7 GS |
60 | C<Symbol::delete_package> wipes out a whole package namespace. Note |
61 | this routine is not exported by default--you may want to import it | |
62 | explicitly. | |
63 | ||
c07a80fd | 64 | =cut |
65 | ||
3dc8e7ab | 66 | BEGIN { require 5.002; } |
c07a80fd | 67 | |
68 | require Exporter; | |
69 | @ISA = qw(Exporter); | |
b42fedfb | 70 | @EXPORT = qw(gensym ungensym qualify qualify_to_ref); |
1ee082b7 | 71 | @EXPORT_OK = qw(delete_package); |
c07a80fd | 72 | |
b42fedfb | 73 | $VERSION = 1.02; |
c07a80fd | 74 | |
75 | my $genpkg = "Symbol::"; | |
76 | my $genseq = 0; | |
77 | ||
7c584b33 | 78 | my %global = map {$_ => 1} qw(ARGV ARGVOUT ENV INC SIG STDERR STDIN STDOUT); |
c07a80fd | 79 | |
6adf1df6 JH |
80 | # |
81 | # Note that we never _copy_ the glob; we just make a ref to it. | |
82 | # If we did copy it, then SVf_FAKE would be set on the copy, and | |
83 | # glob-specific behaviors (e.g. C<*$ref = \&func>) wouldn't work. | |
84 | # | |
c07a80fd | 85 | sub gensym () { |
86 | my $name = "GEN" . $genseq++; | |
6adf1df6 JH |
87 | my $ref = \*{$genpkg . $name}; |
88 | delete $$genpkg{$name}; | |
89 | $ref; | |
c07a80fd | 90 | } |
91 | ||
92 | sub ungensym ($) {} | |
93 | ||
94 | sub qualify ($;$) { | |
95 | my ($name) = @_; | |
49da0595 | 96 | if (!ref($name) && index($name, '::') == -1 && index($name, "'") == -1) { |
c07a80fd | 97 | my $pkg; |
98 | # Global names: special character, "^x", or other. | |
99 | if ($name =~ /^([^a-z])|(\^[a-z])$/i || $global{$name}) { | |
100 | $pkg = "main"; | |
101 | } | |
102 | else { | |
103 | $pkg = (@_ > 1) ? $_[1] : caller; | |
104 | } | |
105 | $name = $pkg . "::" . $name; | |
106 | } | |
107 | $name; | |
108 | } | |
109 | ||
b42fedfb CS |
110 | sub qualify_to_ref ($;$) { |
111 | return \*{ qualify $_[0], @_ > 1 ? $_[1] : caller }; | |
112 | } | |
113 | ||
1ee082b7 GS |
114 | # |
115 | # of Safe.pm lineage | |
116 | # | |
117 | sub delete_package ($) { | |
118 | my $pkg = shift; | |
119 | ||
120 | # expand to full symbol table name if needed | |
121 | ||
122 | unless ($pkg =~ /^main::.*::$/) { | |
123 | $pkg = "main$pkg" if $pkg =~ /^::/; | |
124 | $pkg = "main::$pkg" unless $pkg =~ /^main::/; | |
125 | $pkg .= '::' unless $pkg =~ /::$/; | |
126 | } | |
127 | ||
128 | my($stem, $leaf) = $pkg =~ m/(.*::)(\w+::)$/; | |
129 | my $stem_symtab = *{$stem}{HASH}; | |
130 | return unless defined $stem_symtab and exists $stem_symtab->{$leaf}; | |
131 | ||
c2e66d9e GS |
132 | |
133 | # free all the symbols in the package | |
134 | ||
135 | my $leaf_symtab = *{$stem_symtab->{$leaf}}{HASH}; | |
136 | foreach my $name (keys %$leaf_symtab) { | |
137 | undef *{$pkg . $name}; | |
138 | } | |
139 | ||
140 | # delete the symbol table | |
1ee082b7 GS |
141 | |
142 | %$leaf_symtab = (); | |
143 | delete $stem_symtab->{$leaf}; | |
144 | } | |
145 | ||
c07a80fd | 146 | 1; |