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For ddd2.pl
  Run on Tue May 25 16:52:24 2010
Reported on Tue May 25 16:56:58 2010

File /usr/local/lib/perl5/5.8.8/Exporter.pm
Statements Executed 2046
Statement Execution Time 58.0ms
Subroutines — ordered by exclusive time
Calls P F Exclusive
Time		 Inclusive
Time		 Subroutine
1131134546.4ms71.9msExporter::::importExporter::import
1075125.37ms5.37msExporter::::CORE:matchExporter::CORE:match (opcode)
29315.05ms5.52msExporter::::as_heavyExporter::as_heavy
430222.19ms2.19msExporter::::CORE:substExporter::CORE:subst (opcode)
2243630µs2.12msExporter::::exportExporter::export
666183µs4.14msExporter::::export_ok_tagsExporter::export_ok_tags
11129µs93µsExporter::::require_versionExporter::require_version
0000s0sExporter::::__ANON__[:63]Exporter::__ANON__[:63]
0000s0sExporter::::export_failExporter::export_fail
0000s0sExporter::::export_tagsExporter::export_tags
0000s0sExporter::::export_to_levelExporter::export_to_level
Call graph for these subroutines as a Graphviz dot language file.
Line State
ments		 Time
on line		 Calls Time
in subs		 Code
1package Exporter;
2
315µsrequire 5.006;
4
5# Be lean.
6#use strict;
7#no strict 'refs';
8
915µsour $Debug = 0;
1014µsour $ExportLevel = 0;
11111µsour $Verbose ||= 0;
1215µsour $VERSION = '5.58';
1314µsour (%Cache);
1416µs$Carp::Internal{Exporter} = 1;
15
16
# spent 5.52ms (5.05+470µs) within Exporter::as_heavy which was called 29 times, avg 190µs/call: # 22 times (1.24ms+253µs) by Exporter::export at line 26, avg 68µs/call # 6 times (3.76ms+206µs) by Exporter::export_ok_tags at line 88, avg 660µs/call # once (53µs+11µs) by Exporter::require_version at line 92
sub as_heavy {
1729441µs require Exporter::Heavy;
18 # Unfortunately, this does not work if the caller is aliased as *name = \&foo
19 # Thus the need to create a lot of identical subroutines
2029522µs my $c = (caller(1))[3];
2129837µs29356µs $c =~ s/.*:://;
# spent 356µs making 29 calls to Exporter::CORE:subst, avg 12µs/call
2229603µs \&{"Exporter::Heavy::heavy_$c"};
23}
24
25
# spent 2.12ms (630µs+1.49) within Exporter::export which was called 22 times, avg 96µs/call: # 18 times (520µs+1.22ms) by Exporter::import at line 61, avg 97µs/call # 2 times (53µs+142µs) by IO::Socket::import at line 36 of IO/Socket.pm, avg 98µs/call # once (31µs+72µs) by FileHandle::import at line 73 of FileHandle.pm # once (26µs+57µs) by FileHandle::import at line 81 of FileHandle.pm
sub export {
2622777µs4430.0ms goto &{as_heavy()};
# spent 28.5ms making 22 calls to Exporter::Heavy::heavy_export, avg 1.30ms/call # spent 1.49ms making 22 calls to Exporter::as_heavy, avg 68µs/call
27}
28
29
# spent 71.9ms (46.4+25.5) within Exporter::import which was called 113 times, avg 637µs/call: # once (4.61ms+722µs) by LWP::Protocol::implementor at line 12 of IO/Socket.pm # once (1.34ms+3.19ms) by DBI::install_driver at line 248 of DBD/Pg.pm # once (3.32ms+708µs) by LWP::Protocol::implementor at line 12 of IO/Socket/INET.pm # once (3.30ms+717µs) by LWP::Protocol::implementor at line 12 of IO/Socket/UNIX.pm # once (2.17ms+656µs) by base::import at line 104 of IO/Seekable.pm # once (444µs+1.43ms) by Net::HTTP::Methods::zlib_ok at line 77 of File/Glob.pm # once (418µs+1.30ms) by Net::HTTP::Methods::zlib_ok at line 450 of Compress/Zlib.pm # once (398µs+1.31ms) by Net::HTTP::Methods::zlib_ok at line 15 of IO/Compress/Gzip.pm # once (393µs+1.32ms) by Net::HTTP::Methods::zlib_ok at line 13 of IO/Compress/Zlib/Extra.pm # once (419µs+1.28ms) by Net::HTTP::Methods::zlib_ok at line 16 of IO/Uncompress/Gunzip.pm # once (1.43ms+174µs) by Net::HTTP::Methods::zlib_ok at line 12 of Compress/Zlib.pm # once (532µs+888µs) by Net::HTTP::Methods::zlib_ok at line 11 of IO/Compress/RawDeflate.pm # once (346µs+1.06ms) by Class::DBI::_require_class at line 725 of Class/Date.pm # once (359µs+1.03ms) by Class::DBI::_require_class at line 590 of Class/Date.pm # once (1.20ms+174µs) by Net::HTTP::Methods::zlib_ok at line 8 of IO/Uncompress/RawInflate.pm # once (362µs+1.00ms) by Class::DBI::_require_class at line 20 of Class/Date.pm # once (143µs+1.15ms) by Net::HTTP::Methods::zlib_ok at line 14 of IO/Compress/Gzip.pm # once (1.08ms+145µs) by base::import at line 148 of IO/File.pm # once (1.01ms+170µs) by Net::HTTP::Methods::zlib_ok at line 13 of IO/Compress/Gzip.pm # once (904µs+216µs) by Net::HTTP::Methods::zlib_ok at line 17 of IO/Uncompress/Base.pm # once (911µs+202µs) by base::import at line 39 of FileHandle.pm # once (933µs+152µs) by Net::HTTP::Methods::zlib_ok at line 11 of IO/Compress/Base.pm # once (923µs+154µs) by Net::HTTP::Methods::zlib_ok at line 20 of IO/Uncompress/Base.pm # once (832µs+152µs) by Net::HTTP::Methods::zlib_ok at line 11 of Compress/Zlib.pm # once (842µs+138µs) by Net::HTTP::Methods::zlib_ok at line 9 of IO/Compress/Base.pm # once (149µs+795µs) by Net::HTTP::Methods::zlib_ok at line 144 of IO/Compress/RawDeflate.pm # once (741µs+187µs) by Net::HTTP::Methods::zlib_ok at line 9 of IO/Compress/Adapter/Deflate.pm # once (141µs+768µs) by Net::HTTP::Methods::zlib_ok at line 50 of IO/Uncompress/Gunzip.pm # once (162µs+741µs) by Net::HTTP::Methods::zlib_ok at line 9 of IO/Uncompress/RawInflate.pm # once (143µs+723µs) by Net::HTTP::Methods::zlib_ok at line 15 of IO/Uncompress/Gunzip.pm # once (173µs+634µs) by base::import at line 45 of Storable.pm # once (145µs+615µs) by Net::HTTP::Methods::zlib_ok at line 7 of IO/Uncompress/Adapter/Inflate.pm # once (147µs+585µs) by Net::HTTP::Methods::zlib_ok at line 7 of IO/Compress/Adapter/Deflate.pm # once (391µs+81µs) by base::import at line 31 of Class/DBI/ColumnGrouper.pm # once (406µs+25µs) by Net::HTTP::Methods::zlib_ok at line 17 of IO/Compress/Base.pm # once (357µs+64µs) by base::import at line 30 of Class/DBI.pm # once (321µs+18µs) by LWP::Protocol::implementor at line 178 of Socket.pm # once (294µs+45µs) by Net::HTTP::Methods::zlib_ok at line 23 of IO/Uncompress/Base.pm # once (291µs+43µs) by base::import at line 6 of K2/DB2.pm # once (291µs+29µs) by Net::HTTP::Methods::zlib_ok at line 8 of IO/Uncompress/Adapter/Inflate.pm # once (282µs+31µs) by URI::implementor at line 6 of URI/_server.pm # once (272µs+25µs) by Net::HTTP::Methods::zlib_ok at line 177 of IO/Compress/RawDeflate.pm # once (247µs+24µs) by base::import at line 131 of IO/File.pm # once (243µs+23µs) by Class::DBI::_require_class at line 15 of Class/Date.pm # once (243µs+18µs) by base::import at line 98 of IO/Seekable.pm # once (243µs+17µs) by base::import at line 30 of Class/DBI/ColumnGrouper.pm # once (237µs+17µs) by Net::HTTP::Methods::zlib_ok at line 145 of IO/Compress/RawDeflate.pm # once (234µs+18µs) by Net::HTTP::Methods::zlib_ok at line 21 of IO/Uncompress/Base.pm # once (229µs+19µs) by base::import at line 30 of Class/DBI/Column.pm # once (232µs+16µs) by Net::HTTP::Methods::zlib_ok at line 7 of Compress/Raw/Zlib.pm # once (227µs+19µs) by base::import at line 144 of SQL/Abstract.pm # once (225µs+21µs) by base::import at line 260 of IO/Handle.pm # once (227µs+18µs) by base::import at line 130 of IO/File.pm # once (224µs+19µs) by LWP::Protocol::implementor at line 13 of IO/Socket.pm # once (225µs+18µs) by base::import at line 4 of Class/DBI/Plugin/Pager.pm # once (223µs+19µs) by base::import at line 5 of Clone.pm # once (221µs+21µs) by base::import at line 39 of SelectSaver.pm # once (225µs+17µs) by Net::HTTP::Methods::zlib_ok at line 499 of IO/Compress/Base/Common.pm # once (223µs+17µs) by base::import at line 2 of Data/Page.pm # once (221µs+18µs) by base::import at line 133 of IO/File.pm # once (222µs+16µs) by Net::HTTP::Methods::zlib_ok at line 7 of Compress/Zlib.pm # once (225µs+12µs) by Class::DBI::_require_class at line 19 of Class/Date.pm # once (219µs+18µs) by Class::DBI::_require_class at line 4 of Time/Local.pm # once (218µs+18µs) by Net::HTTP::Methods::zlib_ok at line 7 of IO/Compress/Base/Common.pm # once (219µs+16µs) by Net::HTTP::Methods::zlib_ok at line 5 of File/GlobMapper.pm # once (219µs+15µs) by LWP::Protocol::implementor at line 13 of IO/Socket/INET.pm # once (218µs+16µs) by base::import at line 38 of SelectSaver.pm # once (218µs+16µs) by Net::HTTP::Methods::zlib_ok at line 24 of IO/Uncompress/Base.pm # once (216µs+16µs) by base::import at line 6 of IO.pm # once (211µs+19µs) by LWP::Protocol::implementor at line 13 of IO/Socket/UNIX.pm # once (212µs+16µs) by Class::DBI::_require_class at line 14 of Class/Date.pm # once (209µs+16µs) by Net::HTTP::Methods::zlib_ok at line 16 of IO/Compress/Base.pm # once (206µs+18µs) by base::import at line 259 of IO/Handle.pm # once (209µs+9µs) by URI::implementor at line 5 of URI/_query.pm # once (199µs+13µs) by WWW::Google::PageRank::BEGIN at line 11 of WWW/Google/PageRank.pm # once (195µs+12µs) by Net::HTTP::Methods::zlib_ok at line 12 of IO/Compress/Base.pm # once (190µs+12µs) by Net::HTTP::Methods::zlib_ok at line 8 of IO/Compress/Base/Common.pm # once (187µs+9µs) by base::import at line 7 of K2/DB2.pm # once (183µs+8µs) by Net::HTTP::Methods::zlib_ok at line 14 of IO/Uncompress/Gunzip.pm # once (186µs+0s) by Net::HTTP::Methods::zlib_ok at line 14 of Compress/Zlib.pm # once (175µs+9µs) by URI::implementor at line 7 of URI/_generic.pm # once (175µs+6µs) by Class::DBI::_require_class at line 589 of Class/Date.pm # once (172µs+9µs) by Net::HTTP::Methods::zlib_ok at line 9 of Compress/Zlib.pm # once (173µs+8µs) by base::import at line 6 of Class/DBI/Query.pm # once (166µs+7µs) by Net::HTTP::Methods::zlib_ok at line 22 of IO/Uncompress/Base.pm # once (163µs+0s) by base::import at line 20 of Class/DBI.pm # once (160µs+0s) by Net::HTTP::Methods::zlib_ok at line 13 of Compress/Zlib.pm # once (159µs+0s) by LWP::Protocol::implementor at line 11 of IO/Socket.pm # once (155µs+0s) by Net::HTTP::Methods::zlib_ok at line 9 of IO/Compress/Base/Common.pm # once (155µs+0s) by Net::HTTP::Methods::zlib_ok at line 12 of IO/Compress/RawDeflate.pm # once (149µs+0s) by Net::HTTP::Methods::zlib_ok at line 8 of Compress/Zlib.pm # once (146µs+0s) by Net::HTTP::Methods::zlib_ok at line 12 of IO/Uncompress/RawInflate.pm # once (144µs+0s) by WWW::Google::PageRank::BEGIN at line 10 of WWW/Google/PageRank.pm # once (143µs+0s) by main::BEGIN at line 4 of ddd2.pl # once (143µs+0s) by base::import at line 7 of Ima/DBI.pm # once (143µs+0s) by LWP::Protocol::BEGIN at line 12 of LWP/Protocol.pm # once (142µs+0s) by LWP::Protocol::implementor at line 16 of IO/Socket.pm # once (142µs+0s) by Net::HTTP::Methods::zlib_ok at line 843 of IO/Compress/Base.pm # once (141µs+0s) by main::BEGIN at line 5 of ddd2.pl # once (141µs+0s) by Net::HTTP::Methods::zlib_ok at line 12 of IO/Uncompress/Gunzip.pm # once (139µs+0s) by Net::HTTP::Methods::zlib_ok at line 16 of IO/Compress/Gzip.pm # once (138µs+0s) by base::import at line 6 of Class/DBI/Plugin/Pager.pm # once (138µs+0s) by Net::HTTP::Methods::zlib_ok at line 11 of IO/Uncompress/RawInflate.pm # once (138µs+0s) by Net::HTTP::Methods::zlib_ok at line 10 of IO/Compress/RawDeflate.pm # once (137µs+0s) by Net::HTTP::Methods::zlib_ok at line 11 of IO/Compress/Gzip.pm # once (136µs+0s) by LWP::Protocol::implementor at line 14 of IO/Socket/INET.pm # once (136µs+0s) by LWP::Protocol::implementor at line 17 of IO/Socket.pm # once (131µs+0s) by Net::HTTP::Methods::zlib_ok at line 17 of IO/Uncompress/Gunzip.pm # once (129µs+0s) by Class::DBI::_require_class at line 5 of Class/Date/Const.pm # once (128µs+0s) by Class::DBI::_require_class at line 17 of Class/Date.pm # once (125µs+0s) by Class::DBI::_require_class at line 18 of Class/Date.pm # once (125µs+0s) by base::import at line 7 of Class/DBI/Plugin/Pager.pm # once (118µs+0s) by LWP::Protocol::implementor at line 15 of IO/Socket/INET.pm
sub import {
30113713µs my $pkg = shift;
31113721µs my $callpkg = caller($ExportLevel);
32
33113623µs if ($pkg eq "Exporter" and @_ and $_[0] eq "import") {
34 *{$callpkg."::import"} = \&import;
35 return;
36 }
37
38 # We *need* to treat @{"$pkg\::EXPORT_FAIL"} since Carp uses it :-(
391131.78ms my($exports, $fail) = (\@{"$pkg\::EXPORT"}, \@{"$pkg\::EXPORT_FAIL"});
40113662µs return export $pkg, $callpkg, @_
41 if $Verbose or $Debug or @$fail > 1;
42113810µs my $export_cache = ($Cache{$pkg} ||= {});
431131.74ms my $args = @_ or @_ = @$exports;
44
45113509µs local $_;
46113700µs if ($args and not %$export_cache) {
47 s/^&//, $export_cache->{$_} = 1
48267.39ms4011.83ms foreach (@$exports, @{"$pkg\::EXPORT_OK"});
# spent 1.83ms making 401 calls to Exporter::CORE:subst, avg 5µs/call
49 }
50113569µs my $heavy;
51 # Try very hard not to use {} and hence have to enter scope on the foreach
52 # We bomb out of the loop with last as soon as heavy is set.
531131.19ms if ($args or $fail) {
54 ($heavy = (/\W/ or $args and not exists $export_cache->{$_}
55 or @$fail and $_ eq $fail->[0])) and last
5622619.8ms10755.37ms foreach (@_);
# spent 5.37ms making 1075 calls to Exporter::CORE:match, avg 5µs/call
57 } else {
58 ($heavy = /\W/) and last
59 foreach (@_);
60 }
611131.09ms181.74ms return export $pkg, $callpkg, ($args ? @_ : ()) if $heavy;
# spent 1.74ms making 18 calls to Exporter::export, avg 97µs/call
62 local $SIG{__WARN__} =
63951.40ms sub {require Carp; &Carp::carp};
64 # shortcut for the common case of no type character
6519014.8ms *{"$callpkg\::$_"} = \&{"$pkg\::$_"} foreach @_;
66}
67
68# Default methods
69
70sub export_fail {
71 my $self = shift;
72 @_;
73}
74
75# Unfortunately, caller(1)[3] "does not work" if the caller is aliased as
76# *name = \&foo. Thus the need to create a lot of identical subroutines
77# Otherwise we could have aliased them to export().
78
79sub export_to_level {
80 goto &{as_heavy()};
81}
82
83sub export_tags {
84 goto &{as_heavy()};
85}
86
87
# spent 4.14ms (183µs+3.96) within Exporter::export_ok_tags which was called 6 times, avg 691µs/call: # once (32µs+3.57ms) by base::import at line 259 of DBI.pm # once (31µs+80µs) by Net::HTTP::Methods::zlib_ok at line 28 of IO/Uncompress/RawInflate.pm # once (30µs+81µs) by Net::HTTP::Methods::zlib_ok at line 37 of IO/Compress/Gzip.pm # once (33µs+77µs) by Net::HTTP::Methods::zlib_ok at line 27 of IO/Uncompress/Gunzip.pm # once (30µs+79µs) by Net::HTTP::Methods::zlib_ok at line 63 of IO/Compress/RawDeflate.pm # once (27µs+77µs) by DBI::install_driver at line 68 of DBD/Pg.pm
sub export_ok_tags {
886240µs124.66ms goto &{as_heavy()};
# spent 3.96ms making 6 calls to Exporter::as_heavy, avg 660µs/call # spent 694µs making 6 calls to Exporter::Heavy::heavy_export_ok_tags, avg 116µs/call
89}
90
91
# spent 93µs (29+64) within Exporter::require_version which was called # once (29µs+64µs) by DBI::install_driver at line 71 of DBD/Pg.pm
sub require_version {
92145µs2332µs goto &{as_heavy()};
# spent 268µs making 1 call to Exporter::Heavy::heavy_require_version # spent 64µs making 1 call to Exporter::as_heavy
93}
94
95117µs1;
96__END__
97
98=head1 NAME
99
100Exporter - Implements default import method for modules
101
102=head1 SYNOPSIS
103
104In module YourModule.pm:
105
106 package YourModule;
107 require Exporter;
108 @ISA = qw(Exporter);
109 @EXPORT_OK = qw(munge frobnicate); # symbols to export on request
110
111or
112
113 package YourModule;
114 use Exporter 'import'; # gives you Exporter's import() method directly
115 @EXPORT_OK = qw(munge frobnicate); # symbols to export on request
116
117In other files which wish to use YourModule:
118
119 use ModuleName qw(frobnicate); # import listed symbols
120 frobnicate ($left, $right) # calls YourModule::frobnicate
121
122=head1 DESCRIPTION
123
124The Exporter module implements an C<import> method which allows a module
125to export functions and variables to its users' namespaces. Many modules
126use Exporter rather than implementing their own C<import> method because
127Exporter provides a highly flexible interface, with an implementation optimised
128for the common case.
129
130Perl automatically calls the C<import> method when processing a
131C<use> statement for a module. Modules and C<use> are documented
132in L<perlfunc> and L<perlmod>. Understanding the concept of
133modules and how the C<use> statement operates is important to
134understanding the Exporter.
135
136=head2 How to Export
137
138The arrays C<@EXPORT> and C<@EXPORT_OK> in a module hold lists of
139symbols that are going to be exported into the users name space by
140default, or which they can request to be exported, respectively. The
141symbols can represent functions, scalars, arrays, hashes, or typeglobs.
142The symbols must be given by full name with the exception that the
143ampersand in front of a function is optional, e.g.
144
145 @EXPORT = qw(afunc $scalar @array); # afunc is a function
146 @EXPORT_OK = qw(&bfunc %hash *typeglob); # explicit prefix on &bfunc
147
148If you are only exporting function names it is recommended to omit the
149ampersand, as the implementation is faster this way.
150
151=head2 Selecting What To Export
152
153Do B<not> export method names!
154
155Do B<not> export anything else by default without a good reason!
156
157Exports pollute the namespace of the module user. If you must export
158try to use @EXPORT_OK in preference to @EXPORT and avoid short or
159common symbol names to reduce the risk of name clashes.
160
161Generally anything not exported is still accessible from outside the
162module using the ModuleName::item_name (or $blessed_ref-E<gt>method)
163syntax. By convention you can use a leading underscore on names to
164informally indicate that they are 'internal' and not for public use.
165
166(It is actually possible to get private functions by saying:
167
168 my $subref = sub { ... };
169 $subref->(@args); # Call it as a function
170 $obj->$subref(@args); # Use it as a method
171
172However if you use them for methods it is up to you to figure out
173how to make inheritance work.)
174
175As a general rule, if the module is trying to be object oriented
176then export nothing. If it's just a collection of functions then
177@EXPORT_OK anything but use @EXPORT with caution. For function and
178method names use barewords in preference to names prefixed with
179ampersands for the export lists.
180
181Other module design guidelines can be found in L<perlmod>.
182
183=head2 How to Import
184
185In other files which wish to use your module there are three basic ways for
186them to load your module and import its symbols:
187
188=over 4
189
190=item C<use ModuleName;>
191
192This imports all the symbols from ModuleName's @EXPORT into the namespace
193of the C<use> statement.
194
195=item C<use ModuleName ();>
196
197This causes perl to load your module but does not import any symbols.
198
199=item C<use ModuleName qw(...);>
200
201This imports only the symbols listed by the caller into their namespace.
202All listed symbols must be in your @EXPORT or @EXPORT_OK, else an error
203occurs. The advanced export features of Exporter are accessed like this,
204but with list entries that are syntactically distinct from symbol names.
205
206=back
207
208Unless you want to use its advanced features, this is probably all you
209need to know to use Exporter.
210
211=head1 Advanced features
212
213=head2 Specialised Import Lists
214
215If any of the entries in an import list begins with !, : or / then
216the list is treated as a series of specifications which either add to
217or delete from the list of names to import. They are processed left to
218right. Specifications are in the form:
219
220 [!]name This name only
221 [!]:DEFAULT All names in @EXPORT
222 [!]:tag All names in $EXPORT_TAGS{tag} anonymous list
223 [!]/pattern/ All names in @EXPORT and @EXPORT_OK which match
224
225A leading ! indicates that matching names should be deleted from the
226list of names to import. If the first specification is a deletion it
227is treated as though preceded by :DEFAULT. If you just want to import
228extra names in addition to the default set you will still need to
229include :DEFAULT explicitly.
230
231e.g., Module.pm defines:
232
233 @EXPORT = qw(A1 A2 A3 A4 A5);
234 @EXPORT_OK = qw(B1 B2 B3 B4 B5);
235 %EXPORT_TAGS = (T1 => [qw(A1 A2 B1 B2)], T2 => [qw(A1 A2 B3 B4)]);
236
237 Note that you cannot use tags in @EXPORT or @EXPORT_OK.
238 Names in EXPORT_TAGS must also appear in @EXPORT or @EXPORT_OK.
239
240An application using Module can say something like:
241
242 use Module qw(:DEFAULT :T2 !B3 A3);
243
244Other examples include:
245
246 use Socket qw(!/^[AP]F_/ !SOMAXCONN !SOL_SOCKET);
247 use POSIX qw(:errno_h :termios_h !TCSADRAIN !/^EXIT/);
248
249Remember that most patterns (using //) will need to be anchored
250with a leading ^, e.g., C</^EXIT/> rather than C</EXIT/>.
251
252You can say C<BEGIN { $Exporter::Verbose=1 }> to see how the
253specifications are being processed and what is actually being imported
254into modules.
255
256=head2 Exporting without using Exporter's import method
257
258Exporter has a special method, 'export_to_level' which is used in situations
259where you can't directly call Exporter's import method. The export_to_level
260method looks like:
261
262 MyPackage->export_to_level($where_to_export, $package, @what_to_export);
263
264where $where_to_export is an integer telling how far up the calling stack
265to export your symbols, and @what_to_export is an array telling what
266symbols *to* export (usually this is @_). The $package argument is
267currently unused.
268
269For example, suppose that you have a module, A, which already has an
270import function:
271
272 package A;
273
274 @ISA = qw(Exporter);
275 @EXPORT_OK = qw ($b);
276
277 sub import
278 {
279 $A::b = 1; # not a very useful import method
280 }
281
282and you want to Export symbol $A::b back to the module that called
283package A. Since Exporter relies on the import method to work, via
284inheritance, as it stands Exporter::import() will never get called.
285Instead, say the following:
286
287 package A;
288 @ISA = qw(Exporter);
289 @EXPORT_OK = qw ($b);
290
291 sub import
292 {
293 $A::b = 1;
294 A->export_to_level(1, @_);
295 }
296
297This will export the symbols one level 'above' the current package - ie: to
298the program or module that used package A.
299
300Note: Be careful not to modify C<@_> at all before you call export_to_level
301- or people using your package will get very unexplained results!
302
303=head2 Exporting without inheriting from Exporter
304
305By including Exporter in your @ISA you inherit an Exporter's import() method
306but you also inherit several other helper methods which you probably don't
307want. To avoid this you can do
308
309 package YourModule;
310 use Exporter qw( import );
311
312which will export Exporter's own import() method into YourModule.
313Everything will work as before but you won't need to include Exporter in
314@YourModule::ISA.
315
316=head2 Module Version Checking
317
318The Exporter module will convert an attempt to import a number from a
319module into a call to $module_name-E<gt>require_version($value). This can
320be used to validate that the version of the module being used is
321greater than or equal to the required version.
322
323The Exporter module supplies a default require_version method which
324checks the value of $VERSION in the exporting module.
325
326Since the default require_version method treats the $VERSION number as
327a simple numeric value it will regard version 1.10 as lower than
3281.9. For this reason it is strongly recommended that you use numbers
329with at least two decimal places, e.g., 1.09.
330
331=head2 Managing Unknown Symbols
332
333In some situations you may want to prevent certain symbols from being
334exported. Typically this applies to extensions which have functions
335or constants that may not exist on some systems.
336
337The names of any symbols that cannot be exported should be listed
338in the C<@EXPORT_FAIL> array.
339
340If a module attempts to import any of these symbols the Exporter
341will give the module an opportunity to handle the situation before
342generating an error. The Exporter will call an export_fail method
343with a list of the failed symbols:
344
345 @failed_symbols = $module_name->export_fail(@failed_symbols);
346
347If the export_fail method returns an empty list then no error is
348recorded and all the requested symbols are exported. If the returned
349list is not empty then an error is generated for each symbol and the
350export fails. The Exporter provides a default export_fail method which
351simply returns the list unchanged.
352
353Uses for the export_fail method include giving better error messages
354for some symbols and performing lazy architectural checks (put more
355symbols into @EXPORT_FAIL by default and then take them out if someone
356actually tries to use them and an expensive check shows that they are
357usable on that platform).
358
359=head2 Tag Handling Utility Functions
360
361Since the symbols listed within %EXPORT_TAGS must also appear in either
362@EXPORT or @EXPORT_OK, two utility functions are provided which allow
363you to easily add tagged sets of symbols to @EXPORT or @EXPORT_OK:
364
365 %EXPORT_TAGS = (foo => [qw(aa bb cc)], bar => [qw(aa cc dd)]);
366
367 Exporter::export_tags('foo'); # add aa, bb and cc to @EXPORT
368 Exporter::export_ok_tags('bar'); # add aa, cc and dd to @EXPORT_OK
369
370Any names which are not tags are added to @EXPORT or @EXPORT_OK
371unchanged but will trigger a warning (with C<-w>) to avoid misspelt tags
372names being silently added to @EXPORT or @EXPORT_OK. Future versions
373may make this a fatal error.
374
375=head2 Generating combined tags
376
377If several symbol categories exist in %EXPORT_TAGS, it's usually
378useful to create the utility ":all" to simplify "use" statements.
379
380The simplest way to do this is:
381
382 %EXPORT_TAGS = (foo => [qw(aa bb cc)], bar => [qw(aa cc dd)]);
383
384 # add all the other ":class" tags to the ":all" class,
385 # deleting duplicates
386 {
387 my %seen;
388
389 push @{$EXPORT_TAGS{all}},
390 grep {!$seen{$_}++} @{$EXPORT_TAGS{$_}} foreach keys %EXPORT_TAGS;
391 }
392
393CGI.pm creates an ":all" tag which contains some (but not really
394all) of its categories. That could be done with one small
395change:
396
397 # add some of the other ":class" tags to the ":all" class,
398 # deleting duplicates
399 {
400 my %seen;
401
402 push @{$EXPORT_TAGS{all}},
403 grep {!$seen{$_}++} @{$EXPORT_TAGS{$_}}
404 foreach qw/html2 html3 netscape form cgi internal/;
405 }
406
407Note that the tag names in %EXPORT_TAGS don't have the leading ':'.
408
409=head2 C<AUTOLOAD>ed Constants
410
411Many modules make use of C<AUTOLOAD>ing for constant subroutines to
412avoid having to compile and waste memory on rarely used values (see
413L<perlsub> for details on constant subroutines). Calls to such
414constant subroutines are not optimized away at compile time because
415they can't be checked at compile time for constancy.
416
417Even if a prototype is available at compile time, the body of the
418subroutine is not (it hasn't been C<AUTOLOAD>ed yet). perl needs to
419examine both the C<()> prototype and the body of a subroutine at
420compile time to detect that it can safely replace calls to that
421subroutine with the constant value.
422
423A workaround for this is to call the constants once in a C<BEGIN> block:
424
425 package My ;
426
427 use Socket ;
428
429 foo( SO_LINGER ); ## SO_LINGER NOT optimized away; called at runtime
430 BEGIN { SO_LINGER }
431 foo( SO_LINGER ); ## SO_LINGER optimized away at compile time.
432
433This forces the C<AUTOLOAD> for C<SO_LINGER> to take place before
434SO_LINGER is encountered later in C<My> package.
435
436If you are writing a package that C<AUTOLOAD>s, consider forcing
437an C<AUTOLOAD> for any constants explicitly imported by other packages
438or which are usually used when your package is C<use>d.
439
440=cut
# spent 5.37ms within Exporter::CORE:match which was called 1075 times, avg 5µs/call: # 1075 times (5.37ms+0s) by Exporter::import at line 56 of Exporter.pm, avg 5µs/call
sub Exporter::CORE:match; # xsub
# spent 2.19ms within Exporter::CORE:subst which was called 430 times, avg 5µs/call: # 401 times (1.83ms+0s) by Exporter::import at line 48 of Exporter.pm, avg 5µs/call # 29 times (356µs+0s) by Exporter::as_heavy at line 21 of Exporter.pm, avg 12µs/call
sub Exporter::CORE:subst; # xsub
Report produced by the NYTProf 3.11 Perl profiler, developed by Tim Bunce and Adam Kaplan.