From: M.J.T. Guy <mjtg@cus.cam.ac.uk>
Date: Mon, 24 Mar 1997 17:54:01 +0000 (+0000)
Subject: Exporting UNIVERSAL::can
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=a66bc3b0c7b47b1405c3f62393e8f35e9a4bbdb8;p=p5sagit%2Fp5-mst-13.2.git

Exporting UNIVERSAL::can

UNIVERSAL allows the export of 'isa' but not 'can'.    Since it
is useful to be able to apply 'can' to non-references (to avoid having
to do redundant tests), I offer the following tiny patch.

This also updates the pod to make it slightly clearer that both
functions can be applied to arbitrary values, not just references.

p5p-msgid: E0w9DwX-0000Zr-00@taurus.cus.cam.ac.uk
---

diff --git a/lib/UNIVERSAL.pm b/lib/UNIVERSAL.pm
index c0e7ebd..6d832c4 100644
--- a/lib/UNIVERSAL.pm
+++ b/lib/UNIVERSAL.pm
@@ -2,7 +2,7 @@ package UNIVERSAL;
 
 require Exporter;
 @ISA = qw(Exporter);
-@EXPORT_OK = qw(isa);
+@EXPORT_OK = qw(isa can);
 
 1;
 __END__
@@ -58,7 +58,7 @@ C<UNIVERSAL> also optionally exports the following subroutines
 
 =over 4
 
-=item isa ( REF, TYPE )
+=item isa ( VAL, TYPE )
 
 C<isa> returns I<true> if the first argument is a reference and either
 of the following statements is true.
@@ -67,15 +67,22 @@ of the following statements is true.
 
 =item
 
-C<REF> is a blessed reference and is blessed into package C<TYPE>
+C<VAL> is a blessed reference and is blessed into package C<TYPE>
 or inherits from package C<TYPE>
 
 =item
 
-C<REF> is a reference to a C<TYPE> of perl variable (er 'HASH')
+C<VAL> is a reference to a C<TYPE> of perl variable (er 'HASH')
 
 =back
 
+=item can ( VAL, METHOD )
+
+If C<VAL> is a blessed reference which has a method called C<METHOD>,
+C<can> returns a reference to the subroutine.   If C<VAL> is not
+a blessed reference, or if it does not have a method C<METHOD>,
+I<undef> is returned.
+
 =back
 
 =cut