5 If the first entry in an import list begins with !, : or / then the
6 list is treated as a series of specifications which either add to or
7 delete from the list of names to import. They are processed left to
8 right. Specifications are in the form:
10 [!]name This name only
11 [!]:DEFAULT All names in @EXPORT
12 [!]:tag All names in $EXPORT_TAGS{tag} anonymous list
13 [!]/pattern/ All names in @EXPORT and @EXPORT_OK which match
15 A leading ! indicates that matching names should be deleted from the
16 list of names to import. If the first specification is a deletion it
17 is treated as though preceded by :DEFAULT. If you just want to import
18 extra names in addition to the default set you will still need to
19 include :DEFAULT explicitly.
21 e.g., Module.pm defines:
23 @EXPORT = qw(A1 A2 A3 A4 A5);
24 @EXPORT_OK = qw(B1 B2 B3 B4 B5);
25 %EXPORT_TAGS = (T1 => [qw(A1 A2 B1 B2)], T2 => [qw(A1 A2 B3 B4)]);
27 Note that you cannot use tags in @EXPORT or @EXPORT_OK.
28 Names in EXPORT_TAGS must also appear in @EXPORT or @EXPORT_OK.
32 use Module qw(:DEFAULT :T2 !B3 A3);
33 use Socket qw(!/^[AP]F_/ !SOMAXCONN !SOL_SOCKET);
34 use POSIX qw(/^S_/ acos asin atan /^E/ !/^EXIT/);
36 You can set C<$Exporter::Verbose=1;> to see how the specifications are
37 being processed and what is actually being imported into modules.
39 =head2 Module Version Checking
41 The Exporter module will convert an attempt to import a number from a
42 module into a call to $module_name->require_version($value). This can
43 be used to validate that the version of the module being used is
44 greater than or equal to the required version.
46 The Exporter module supplies a default require_version method which
47 checks the value of $VERSION in the exporting module.
60 # First make import warnings look like they're coming from the "use".
61 local $SIG{__WARN__} = sub {
63 $text =~ s/ at \S*Exporter.pm line \d+.\n//;
64 local $Carp::CarpLevel = 1; # ignore package calling us too.
72 *exports = \@{"${pkg}::EXPORT"};
75 *exports = \%{"${pkg}::EXPORT"};
77 grep(s/^&//, @exports);
78 @exports{@exports} = (1) x @exports;
79 foreach $extra (@{"${pkg}::EXPORT_OK"}) {
84 if ($imports[0] =~ m#^[/!:]#){
85 my(@allexports) = keys %exports;
86 my $tagsref = \%{"${pkg}::EXPORT_TAGS"};
89 # negated first item implies starting with default set:
90 unshift(@imports, ':DEFAULT') if $imports[0] =~ m/^!/;
93 my($mode,$spec) = m/^(!)?(.*)/;
94 $mode = '+' unless defined $mode;
96 @names = ($spec); # default, maybe overridden below
98 if ($spec =~ m:^/(.*)/$:){
100 @names = grep(/$patn/, @allexports); # XXX anchor by default?
102 elsif ($spec =~ m#^:(.*)# and $tagsref){
103 if ($1 eq 'DEFAULT'){
106 elsif ($tagsref and $tagdata = $tagsref->{$1}) {
111 warn "Import Mode $mode, Spec $spec, Names @names\n" if $Verbose;
113 map {delete $imports{$_}} @names; # delete @imports{@names} would be handy :-)
116 @imports{@names} = (1) x @names;
119 @imports = keys %imports;
122 foreach $sym (@imports) {
123 if (!$exports{$sym}) {
124 if ($sym =~ m/^\d/) {
125 $pkg->require_version($sym);
126 # If the version number was the only thing specified
127 # then we should act as if nothing was specified:
132 } elsif ($sym !~ s/^&// || !$exports{$sym}) {
133 warn qq["$sym" is not exported by the $pkg module ],
134 "at $callfile line $callline\n";
140 Carp::croak("Can't continue with import errors.\n") if $oops;
145 warn "Importing from $pkg into $callpkg: ",
146 join(", ",@imports),"\n" if ($Verbose && @imports);
147 foreach $sym (@imports) {
149 $type = $1 if $sym =~ s/^(\W)//;
150 *{"${callpkg}::$sym"} =
151 $type eq '&' ? \&{"${pkg}::$sym"} :
152 $type eq '$' ? \${"${pkg}::$sym"} :
153 $type eq '@' ? \@{"${pkg}::$sym"} :
154 $type eq '%' ? \%{"${pkg}::$sym"} :
155 $type eq '*' ? *{"${pkg}::$sym"} :
156 warn "Can't export symbol: $type$sym\n";
161 local ($callpkg, $callfile, $callline) = caller($ExportLevel);
163 export $pkg, $callpkg, @_;
168 *tags = \%{"${pkg}::EXPORT_TAGS"};
169 push(@{"${pkg}::EXPORT"},
170 map {$tags{$_} ? @{$tags{$_}} : $_} @_ ? @_ : keys %tags);
173 sub require_version {
174 my($self, $wanted) = @_;
175 my $pkg = ref $self || $self;
176 my $version = ${"${pkg}::VERSION"} || "(undef)";
177 Carp::croak("$pkg $wanted required--this is only version $version")
178 if $version < $wanted;