# anything unless called on UNIVERSAL.
sub import {
return unless $_[0] eq __PACKAGE__;
+ require warnings;
+ warnings::warnif(
+ 'deprecated',
+ 'UNIVERSAL->import is deprecated and will be removed in a future perl',
+ );
goto &Exporter::import;
}
Again, the same rule about having a valid invocant applies -- use an C<eval>
block or C<blessed> if you need to be extra paranoid.
-B<NOTE:> C<can> directly uses Perl's internal code for method lookup, and
-C<isa> uses a very similar method and cache-ing strategy. This may cause
-strange effects if the Perl code dynamically changes @ISA in any package.
-
-You may add other methods to the UNIVERSAL class via Perl or XS code.
-You do not need to C<use UNIVERSAL> to make these methods
-available to your program (and you should not do so).
-
=item C<VERSION ( [ REQUIRE ] )>
C<VERSION> will return the value of the variable C<$VERSION> in the
=back
+=head1 WARNINGS
+
+B<NOTE:> C<can> directly uses Perl's internal code for method lookup, and
+C<isa> uses a very similar method and cache-ing strategy. This may cause
+strange effects if the Perl code dynamically changes @ISA in any package.
+
+You may add other methods to the UNIVERSAL class via Perl or XS code.
+You do not need to C<use UNIVERSAL> to make these methods
+available to your program (and you should not do so).
+
=head1 EXPORTS
None by default.
You may request the import of three functions (C<isa>, C<can>, and C<VERSION>),
-however it is usually harmful to do so. Please don't do this in new code.
+B<but this feature is deprecated and will be removed>. Please don't do this in
+new code.
For example, previous versions of this documentation suggested using C<isa> as
a function to determine the type of a reference: