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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 | ||
4379a6f8 | 18 | # replace *FOO{IO} handle but not $FOO, %FOO, etc. |
ae716a98 | 19 | *FOO = geniosym; |
ae716a98 | 20 | |
c07a80fd | 21 | print qualify("x"), "\n"; # "Test::x" |
22 | print qualify("x", "FOO"), "\n" # "FOO::x" | |
23 | print qualify("BAR::x"), "\n"; # "BAR::x" | |
24 | print qualify("BAR::x", "FOO"), "\n"; # "BAR::x" | |
25 | print qualify("STDOUT", "FOO"), "\n"; # "main::STDOUT" (global) | |
26 | print qualify(\*x), "\n"; # returns \*x | |
27 | print qualify(\*x, "FOO"), "\n"; # returns \*x | |
28 | ||
b42fedfb CS |
29 | use strict refs; |
30 | print { qualify_to_ref $fh } "foo!\n"; | |
31 | $ref = qualify_to_ref $name, $pkg; | |
32 | ||
1ee082b7 GS |
33 | use Symbol qw(delete_package); |
34 | delete_package('Foo::Bar'); | |
35 | print "deleted\n" unless exists $Foo::{'Bar::'}; | |
36 | ||
37 | ||
c07a80fd | 38 | =head1 DESCRIPTION |
39 | ||
40 | C<Symbol::gensym> creates an anonymous glob and returns a reference | |
41 | to it. Such a glob reference can be used as a file or directory | |
42 | handle. | |
43 | ||
44 | For backward compatibility with older implementations that didn't | |
45 | support anonymous globs, C<Symbol::ungensym> is also provided. | |
46 | But it doesn't do anything. | |
47 | ||
ae716a98 YST |
48 | C<Symbol::geniosym> creates an anonymous IO handle. This can be |
49 | assigned into an existing glob without affecting the non-IO portions | |
50 | of the glob. | |
51 | ||
c07a80fd | 52 | C<Symbol::qualify> turns unqualified symbol names into qualified |
7c584b33 | 53 | variable names (e.g. "myvar" -E<gt> "MyPackage::myvar"). If it is given a |
c07a80fd | 54 | second parameter, C<qualify> uses it as the default package; |
55 | otherwise, it uses the package of its caller. Regardless, global | |
f610777f | 56 | variable names (e.g. "STDOUT", "ENV", "SIG") are always qualified with |
c07a80fd | 57 | "main::". |
58 | ||
59 | Qualification applies only to symbol names (strings). References are | |
60 | left unchanged under the assumption that they are glob references, | |
61 | which are qualified by their nature. | |
62 | ||
b42fedfb CS |
63 | C<Symbol::qualify_to_ref> is just like C<Symbol::qualify> except that it |
64 | returns a glob ref rather than a symbol name, so you can use the result | |
65 | even if C<use strict 'refs'> is in effect. | |
66 | ||
1ee082b7 GS |
67 | C<Symbol::delete_package> wipes out a whole package namespace. Note |
68 | this routine is not exported by default--you may want to import it | |
69 | explicitly. | |
70 | ||
c07a80fd | 71 | =cut |
72 | ||
c74f62b5 | 73 | BEGIN { require 5.005; } |
c07a80fd | 74 | |
75 | require Exporter; | |
76 | @ISA = qw(Exporter); | |
b42fedfb | 77 | @EXPORT = qw(gensym ungensym qualify qualify_to_ref); |
ae716a98 | 78 | @EXPORT_OK = qw(delete_package geniosym); |
c07a80fd | 79 | |
c74f62b5 | 80 | $VERSION = 1.04; |
c07a80fd | 81 | |
82 | my $genpkg = "Symbol::"; | |
83 | my $genseq = 0; | |
84 | ||
7c584b33 | 85 | my %global = map {$_ => 1} qw(ARGV ARGVOUT ENV INC SIG STDERR STDIN STDOUT); |
c07a80fd | 86 | |
6adf1df6 JH |
87 | # |
88 | # Note that we never _copy_ the glob; we just make a ref to it. | |
89 | # If we did copy it, then SVf_FAKE would be set on the copy, and | |
90 | # glob-specific behaviors (e.g. C<*$ref = \&func>) wouldn't work. | |
91 | # | |
c07a80fd | 92 | sub gensym () { |
93 | my $name = "GEN" . $genseq++; | |
6adf1df6 JH |
94 | my $ref = \*{$genpkg . $name}; |
95 | delete $$genpkg{$name}; | |
96 | $ref; | |
c07a80fd | 97 | } |
98 | ||
ae716a98 YST |
99 | sub geniosym () { |
100 | my $sym = gensym(); | |
101 | # force the IO slot to be filled | |
102 | select(select $sym); | |
103 | *$sym{IO}; | |
104 | } | |
105 | ||
c07a80fd | 106 | sub ungensym ($) {} |
107 | ||
108 | sub qualify ($;$) { | |
109 | my ($name) = @_; | |
49da0595 | 110 | if (!ref($name) && index($name, '::') == -1 && index($name, "'") == -1) { |
c07a80fd | 111 | my $pkg; |
c74f62b5 RGS |
112 | # Global names: special character, "^xyz", or other. |
113 | if ($name =~ /^(([^a-z])|(\^[a-z_]+))\z/i || $global{$name}) { | |
114 | # RGS 2001-11-05 : translate leading ^X to control-char | |
115 | $name =~ s/^\^([a-z_])/'qq(\c'.$1.')'/eei; | |
c07a80fd | 116 | $pkg = "main"; |
117 | } | |
118 | else { | |
119 | $pkg = (@_ > 1) ? $_[1] : caller; | |
120 | } | |
121 | $name = $pkg . "::" . $name; | |
122 | } | |
123 | $name; | |
124 | } | |
125 | ||
b42fedfb CS |
126 | sub qualify_to_ref ($;$) { |
127 | return \*{ qualify $_[0], @_ > 1 ? $_[1] : caller }; | |
128 | } | |
129 | ||
1ee082b7 GS |
130 | # |
131 | # of Safe.pm lineage | |
132 | # | |
133 | sub delete_package ($) { | |
134 | my $pkg = shift; | |
135 | ||
136 | # expand to full symbol table name if needed | |
137 | ||
138 | unless ($pkg =~ /^main::.*::$/) { | |
139 | $pkg = "main$pkg" if $pkg =~ /^::/; | |
140 | $pkg = "main::$pkg" unless $pkg =~ /^main::/; | |
141 | $pkg .= '::' unless $pkg =~ /::$/; | |
142 | } | |
143 | ||
144 | my($stem, $leaf) = $pkg =~ m/(.*::)(\w+::)$/; | |
145 | my $stem_symtab = *{$stem}{HASH}; | |
146 | return unless defined $stem_symtab and exists $stem_symtab->{$leaf}; | |
147 | ||
c2e66d9e GS |
148 | |
149 | # free all the symbols in the package | |
150 | ||
151 | my $leaf_symtab = *{$stem_symtab->{$leaf}}{HASH}; | |
152 | foreach my $name (keys %$leaf_symtab) { | |
153 | undef *{$pkg . $name}; | |
154 | } | |
155 | ||
156 | # delete the symbol table | |
1ee082b7 GS |
157 | |
158 | %$leaf_symtab = (); | |
159 | delete $stem_symtab->{$leaf}; | |
160 | } | |
161 | ||
c07a80fd | 162 | 1; |