require 5.001;
+#
+# We go to a lot of trouble not to 'require Carp' at file scope,
+# because Carp requires Exporter, and something has to give.
+#
+
$ExportLevel = 0;
$Verbose = 0 unless $Verbose;
-require Carp;
-
sub export {
# First make import warnings look like they're coming from the "use".
local $SIG{__WARN__} = sub {
my $text = shift;
- $text =~ s/ at \S*Exporter.pm line \d+.*\n//;
- local $Carp::CarpLevel = 1; # ignore package calling us too.
- Carp::carp($text);
+ if ($text =~ s/ at \S*Exporter.pm line \d+.*\n//) {
+ require Carp;
+ local $Carp::CarpLevel = 1; # ignore package calling us too.
+ Carp::carp($text);
+ }
+ else {
+ warn $text;
+ }
};
local $SIG{__DIE__} = sub {
+ require Carp;
+ local $Carp::CarpLevel = 1; # ignore package calling us too.
Carp::croak("$_[0]Illegal null symbol in \@${1}::EXPORT")
if $_[0] =~ /^Unable to create sub named "(.*?)::"/;
};
last;
}
} elsif ($sym !~ s/^&// || !$exports{$sym}) {
- warn qq["$sym" is not exported by the $pkg module];
+ require Carp;
+ Carp::carp(qq["$sym" is not exported by the $pkg module]);
$oops++;
}
}
}
- Carp::croak("Can't continue after import errors") if $oops;
+ if ($oops) {
+ require Carp;
+ Carp::croak("Can't continue after import errors");
+ }
}
else {
@imports = @exports;
if (@failed) {
@failed = $pkg->export_fail(@failed);
foreach $sym (@failed) {
- warn qq["$sym" is not implemented by the $pkg module ],
- "on this architecture";
+ require Carp;
+ Carp::carp(qq["$sym" is not implemented by the $pkg module ],
+ "on this architecture");
+ }
+ if (@failed) {
+ require Carp;
+ Carp::croak("Can't continue after import errors");
}
- Carp::croak("Can't continue after import errors") if @failed;
}
}
$type eq '@' ? \@{"${pkg}::$sym"} :
$type eq '%' ? \%{"${pkg}::$sym"} :
$type eq '*' ? *{"${pkg}::$sym"} :
- Carp::croak("Can't export symbol: $type$sym");
+ do { require Carp; Carp::croak("Can't export symbol: $type$sym") };
}
}
+sub export_to_level
+{
+ my $pkg = shift;
+ my ($level, $junk) = (shift, shift); # need to get rid of first arg
+ # we know it already.
+ my $callpkg = caller($level);
+ $pkg->export($callpkg, @_);
+}
+
sub import {
my $pkg = shift;
my $callpkg = caller($ExportLevel);
}
+
# Utility functions
sub _push_tags {
push(@{"${pkg}::$var"},
map { $export_tags{$_} ? @{$export_tags{$_}} : scalar(++$nontag,$_) }
(@$syms) ? @$syms : keys %export_tags);
- # This may change to a die one day
- Carp::carp("Some names are not tags") if $nontag and $^W;
+ if ($nontag and $^W) {
+ # This may change to a die one day
+ require Carp;
+ Carp::carp("Some names are not tags");
+ }
}
sub export_tags { _push_tags((caller)[0], "EXPORT", \@_) }
$version ||= "(undef)";
my $file = $INC{"$pkg.pm"};
$file &&= " ($file)";
+ require Carp;
Carp::croak("$pkg $wanted required--this is only version $version$file")
}
$version;
=head1 DESCRIPTION
The Exporter module implements a default C<import> method which
-many modules choose inherit rather than implement their own.
+many modules choose to inherit rather than implement their own.
Perl automatically calls the C<import> method when processing a
C<use> statement for a module. Modules and C<use> are documented
specifications are being processed and what is actually being imported
into modules.
+=head2 Exporting without using Export's import method
+
+Exporter has a special method, 'export_to_level' which is used in situations
+where you can't directly call Export's import method. The export_to_level
+method looks like:
+
+MyPackage->export_to_level($where_to_export, @what_to_export);
+
+where $where_to_export is an integer telling how far up the calling stack
+to export your symbols, and @what_to_export is an array telling what
+symbols *to* export (usually this is @_).
+
+For example, suppose that you have a module, A, which already has an
+import function:
+
+package A;
+
+@ISA = qw(Exporter);
+@EXPORT_OK = qw ($b);
+
+sub import
+{
+ $A::b = 1; # not a very useful import method
+}
+
+and you want to Export symbol $A::b back to the module that called
+package A. Since Exporter relies on the import method to work, via
+inheritance, as it stands Exporter::import() will never get called.
+Instead, say the following:
+
+package A;
+@ISA = qw(Exporter);
+@EXPORT_OK = qw ($b);
+
+sub import
+{
+ $A::b = 1;
+ A->export_to_level(1, @_);
+}
+
+This will export the symbols one level 'above' the current package - ie: to
+the program or module that used package A.
+
+Note: Be careful not to modify '@_' at all before you call export_to_level
+- or people using your package will get very unexplained results!
+
+
=head2 Module Version Checking
The Exporter module will convert an attempt to import a number from a
The names of any symbols that cannot be exported should be listed
in the C<@EXPORT_FAIL> array.
-If a module attempts to import any of these symbols the Exporter will
+If a module attempts to import any of these symbols the Exporter
will give the module an opportunity to handle the situation before
generating an error. The Exporter will call an export_fail method
with a list of the failed symbols: