diff options
| -rw-r--r-- | lib/UNIVERSAL.pm | 69 |
1 files changed, 49 insertions, 20 deletions
diff --git a/lib/UNIVERSAL.pm b/lib/UNIVERSAL.pm index 92b4fcd352..5c28f9fbf8 100644 --- a/lib/UNIVERSAL.pm +++ b/lib/UNIVERSAL.pm @@ -41,20 +41,42 @@ C<UNIVERSAL> provides the following methods and functions: =over 4 -=item $obj->isa( TYPE ), CLASS->isa( TYPE ), isa( VAL, TYPE ) +=item C<< $obj->isa( TYPE ) >> - C<TYPE> is a package name - $obj is a blessed reference or a string containing a package name - C<CLASS> is a package name - C<VAL> is any of the above or an unblessed reference +=item C<< CLASS->isa( TYPE ) >> -When used as an instance or class method (C<$obj->isa( TYPE )>), C<isa> -returns I<true> if $obj is blessed into package C<TYPE> or inherits from -package C<TYPE>. +=item C<isa( VAL, TYPE )> -When used as a class method (C<CLASS->isa( TYPE )>; sometimes referred to as a -static method), C<isa> returns I<true> if C<CLASS> inherits from (or is itself) -the name of the package C<TYPE> or inherits from package C<TYPE>. +Where + +=over 4 + +=item C<TYPE> + +is a package name + +=item C<$obj> + +is a blessed reference or a string containing a package name + +=item C<CLASS> + +is a package name + +=item C<VAL> + +is any of the above or an unblessed reference + +=back + +When used as an instance or class method (C<< $obj->isa( TYPE ) >>), +C<isa> returns I<true> if $obj is blessed into package C<TYPE> or +inherits from package C<TYPE>. + +When used as a class method (C<< CLASS->isa( TYPE ) >>: sometimes +referred to as a static method), C<isa> returns I<true> if C<CLASS> +inherits from (or is itself) the name of the package C<TYPE> or +inherits from package C<TYPE>. When used as a function, like @@ -67,11 +89,15 @@ or require UNIVERSAL ; $yes = UNIVERSAL::isa $a, "ARRAY"; -, C<isa> returns I<true> in the same cases as above and also if C<VAL> is an +C<isa> returns I<true> in the same cases as above and also if C<VAL> is an unblessed reference to a perl variable of type C<TYPE>, such as "HASH", "ARRAY", or "Regexp". -=item $obj->can( METHOD ), CLASS->can( METHOD ), can( VAL, METHOD ) +=item C<< $obj->can( METHOD ) >> + +=item C<< CLASS->can( METHOD ) >> + +=item C<can( VAL, METHOD )> C<can> checks if the object or class has a method called C<METHOD>. If it does then a reference to the sub is returned. If it does not then I<undef> is @@ -95,24 +121,27 @@ has a method called C<METHOD>, C<can> returns a reference to the subroutine. If C<VAL> is not a blessed reference, or if it does not have a method C<METHOD>, I<undef> is returned. -=item VERSION ( [ REQUIRE ] ) +=item C<VERSION ( [ REQUIRE ] )> C<VERSION> will return the value of the variable C<$VERSION> in the package the object is blessed into. If C<REQUIRE> is given then it will do a comparison and die if the package version is not greater than or equal to C<REQUIRE>. -C<VERSION> can be called as either a class (static) method, an object method or -or a function. +C<VERSION> can be called as either a class (static) method, an object +method or a function. =back -These subroutines should I<not> be imported via S<C<use UNIVERSAL qw(...)>>. -If you want simple local access to them you can do +=head1 EXPORTS - *isa = \&UNIVERSAL::isa; +None by default. -to import isa into your package. +You may request the import of all three functions (C<isa>, C<can>, and +C<VERSION>), however it isn't usually necessary to do so. Perl magically +makes these functions act as methods on all objects. The one exception is +C<isa>, which is useful as a function when operating on non-blessed +references. =cut |