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| author | M.J.T. Guy <mjtg@cus.cam.ac.uk> | 1997-03-24 17:54:01 +0000 |
|---|---|---|
| committer | Chip Salzenberg <chip@atlantic.net> | 1997-03-22 15:34:25 +1200 |
| commit | a66bc3b0c7b47b1405c3f62393e8f35e9a4bbdb8 (patch) | |
| tree | 974f77f3eca3a27195bbee3cd1ac1bdeafb62020 /lib/UNIVERSAL.pm | |
| parent | 590feb52ba1fa31a38ae6316de4289419c5c6da0 (diff) | |
| download | perl-a66bc3b0c7b47b1405c3f62393e8f35e9a4bbdb8.tar.gz | |
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
Diffstat (limited to 'lib/UNIVERSAL.pm')
| -rw-r--r-- | lib/UNIVERSAL.pm | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/lib/UNIVERSAL.pm b/lib/UNIVERSAL.pm index c0e7ebdee2..6d832c4bea 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 |