File Manager

X7ROOT File Manager

Current Path: /usr/share/perl5

📁 ..
📄 AnyDBM_File.pm(2.56 KB)
📁 App
📁 Archive
📁 Attribute
📄 AutoLoader.pm(14.66 KB)
📄 AutoSplit.pm(19.18 KB)
📁 B
📄 Benchmark.pm(27.87 KB)
📄 CORE.pod(2.7 KB)
📁 CPAN
📄 CPAN.pm(132.91 KB)
📁 Class
📁 Compress
📁 Config
📄 DB.pm(18.43 KB)
📁 DBM_Filter
📄 DBM_Filter.pm(14.06 KB)
📁 Devel
📄 DirHandle.pm(1.52 KB)
📄 Dumpvalue.pm(16.5 KB)
📁 Encode
📄 English.pm(4.34 KB)
📁 ExtUtils
📁 File
📄 FileCache.pm(5.44 KB)
📄 FileHandle.pm(6.62 KB)
📁 Filter
📄 FindBin.pm(4.45 KB)
📁 Getopt
📁 HTTP
📁 I18N
📁 IO
📁 IPC
📁 JSON
📁 LWP
📄 LWP.pm(21.15 KB)
📁 Locale
📁 Log
📁 Math
📁 Memoize
📄 Memoize.pm(34.4 KB)
📁 Module
📄 NEXT.pm(18.05 KB)
📁 Net
📁 Object
📁 Package
📁 Perl
📁 PerlIO
📄 PerlIO.pm(10.19 KB)
📁 Pod
📄 Safe.pm(24.03 KB)
📁 Search
📄 SelectSaver.pm(1.05 KB)
📄 SelfLoader.pm(16.97 KB)
📄 Symbol.pm(4.68 KB)
📁 Term
📁 Test
📄 Test.pm(28.13 KB)
📁 Text
📁 Thread
📄 Thread.pm(8.09 KB)
📁 Tie
📁 Time
📄 UNIVERSAL.pm(6.97 KB)
📁 URI
📄 URI.pm(33.01 KB)
📁 Unicode
📁 User
📁 Version
📄 XSLoader.pm(9.99 KB)
📄 _charnames.pm(29.8 KB)
📄 autouse.pm(4.14 KB)
📄 base.pm(6.37 KB)
📄 bigint.pm(17.44 KB)
📄 bignum.pm(18.23 KB)
📄 bigrat.pm(14.11 KB)
📄 blib.pm(2.04 KB)
📄 bytes.pm(2.96 KB)
📄 bytes_heavy.pl(758 B)
📄 charnames.pm(19.22 KB)
📄 deprecate.pm(3.01 KB)
📄 diagnostics.pm(17.96 KB)
📄 dumpvar.pl(14.96 KB)
📁 encoding
📄 feature.pm(11.06 KB)
📄 fields.pm(9.28 KB)
📄 filetest.pm(3.91 KB)
📄 if.pm(1.13 KB)
📄 integer.pm(3.19 KB)
📄 less.pm(3.13 KB)
📄 locale.pm(2.72 KB)
📄 lwpcook.pod(9.05 KB)
📄 lwptut.pod(24.89 KB)
📄 open.pm(7.83 KB)
📁 overload
📄 overload.pm(52.66 KB)
📄 overloading.pm(1.77 KB)
📄 perl5db.pl(302.79 KB)
📄 perlfaq.pm(94 B)
📁 pod
📄 sigtrap.pm(7.46 KB)
📄 sort.pm(5.95 KB)
📄 strict.pm(3.84 KB)
📄 subs.pm(845 B)
📁 unicore
📄 utf8.pm(7.6 KB)
📄 utf8_heavy.pl(30.1 KB)
📄 vars.pm(2.3 KB)
📁 vendor_perl
📄 vmsish.pm(4.22 KB)
📁 warnings
📄 warnings.pm(18.34 KB)

Editing: UNIVERSAL.pm

package UNIVERSAL;

our $VERSION = '1.11';

# UNIVERSAL should not contain any extra subs/methods beyond those
# that it exists to define. The use of Exporter below is a historical
# accident that can't be fixed without breaking code.  Note that we
# *don't* set @ISA here, as we don't want all classes/objects inheriting from
# Exporter.  It's bad enough that all classes have a import() method
# whenever UNIVERSAL.pm is loaded.
require Exporter;
@EXPORT_OK = qw(isa can VERSION);

# Make sure that even though the import method is called, it doesn't do
# anything unless called on UNIVERSAL.
sub import {
    return unless $_[0] eq __PACKAGE__;
    return unless @_ > 1;
    require warnings;
    warnings::warnif(
      'deprecated',
      'UNIVERSAL->import is deprecated and will be removed in a future perl',
    );
    goto &Exporter::import;
}

1;
__END__

=head1 NAME

UNIVERSAL - base class for ALL classes (blessed references)

=head1 SYNOPSIS

$is_io    = $fd->isa("IO::Handle");
    $is_io    = Class->isa("IO::Handle");

$does_log = $obj->DOES("Logger");
    $does_log = Class->DOES("Logger");

$sub      = $obj->can("print");
    $sub      = Class->can("print");

$sub      = eval { $ref->can("fandango") };
    $ver      = $obj->VERSION;

# but never do this!
    $is_io    = UNIVERSAL::isa($fd, "IO::Handle");
    $sub      = UNIVERSAL::can($obj, "print");

=head1 DESCRIPTION

C<UNIVERSAL> is the base class from which all blessed references inherit.
See L<perlobj>.

C<UNIVERSAL> provides the following methods:

=over 4

=item C<< $obj->isa( TYPE ) >>

=item C<< CLASS->isa( TYPE ) >>

=item C<< eval { VAL->isa( TYPE ) } >>

Where

=over 4

=item C<TYPE>

is a package name

=item C<$obj>

is a blessed reference or 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>.

If you're not sure what you have (the C<VAL> case), wrap the method call in an
C<eval> block to catch the exception if C<VAL> is undefined.

If you want to be sure that you're calling C<isa> as a method, not a class,
check the invocand with C<blessed> from L<Scalar::Util> first:

use Scalar::Util 'blessed';

if ( blessed( $obj ) && $obj->isa("Some::Class") ) {
      ...
  }

=item C<< $obj->DOES( ROLE ) >>

=item C<< CLASS->DOES( ROLE ) >>

C<DOES> checks if the object or class performs the role C<ROLE>.  A role is a
named group of specific behavior (often methods of particular names and
signatures), similar to a class, but not necessarily a complete class by
itself.  For example, logging or serialization may be roles.

C<DOES> and C<isa> are similar, in that if either is true, you know that the
object or class on which you call the method can perform specific behavior.
However, C<DOES> is different from C<isa> in that it does not care I<how> the
invocand performs the operations, merely that it does.  (C<isa> of course
mandates an inheritance relationship.  Other relationships include aggregation,
delegation, and mocking.)

By default, classes in Perl only perform the C<UNIVERSAL> role, as well as the
role of all classes in their inheritance.  In other words, by default C<DOES>
responds identically to C<isa>.

There is a relationship between roles and classes, as each class implies the
existence of a role of the same name.  There is also a relationship between
inheritance and roles, in that a subclass that inherits from an ancestor class
implicitly performs any roles its parent performs.  Thus you can use C<DOES> in
place of C<isa> safely, as it will return true in all places where C<isa> will
return true (provided that any overridden C<DOES> I<and> C<isa> methods behave
appropriately).

=item C<< $obj->can( METHOD ) >>

=item C<< CLASS->can( METHOD ) >>

=item C<< eval { VAL->can( METHOD ) } >>

C<can> checks if the object or class has a method called C<METHOD>. If it does,
then it returns a reference to the sub.  If it does not, then it returns
I<undef>.  This includes methods inherited or imported by C<$obj>, C<CLASS>, or
C<VAL>.

C<can> cannot know whether an object will be able to provide a method through
AUTOLOAD (unless the object's class has overridden C<can> appropriately), so a
return value of I<undef> does not necessarily mean the object will not be able
to handle the method call. To get around this some module authors use a forward
declaration (see L<perlsub>) for methods they will handle via AUTOLOAD. For
such 'dummy' subs, C<can> will still return a code reference, which, when
called, will fall through to the AUTOLOAD. If no suitable AUTOLOAD is provided,
calling the coderef will cause an error.

You may call C<can> as a class (static) method or an object method.

Again, the same rule about having a valid invocand applies -- use an C<eval>
block or C<blessed> if you need to be extra paranoid.

=item C<VERSION ( [ REQUIRE ] )>

C<VERSION> will return the value of the variable C<$VERSION> in the
package the object is blessed into. If C<REQUIRE> is given then
it will do a comparison and die if the package version is not
greater than or equal to C<REQUIRE>, or if either C<$VERSION> or C<REQUIRE>
is not a "lax" version number (as defined by the L<version> module).

The return from C<VERSION> will actually be the stringified version object
using the package C<$VERSION> scalar, which is guaranteed to be equivalent
but may not be precisely the contents of the C<$VERSION> scalar.  If you want
the actual contents of C<$VERSION>, use C<$CLASS::VERSION> instead.

C<VERSION> can be called as either a class (static) method or an object
method.

=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>),
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:

use UNIVERSAL 'isa';

$yes = isa $h, "HASH";
  $yes = isa "Foo", "Bar";

The problem is that this code will I<never> call an overridden C<isa> method in
any class.  Instead, use C<reftype> from L<Scalar::Util> for the first case:

use Scalar::Util 'reftype';

$yes = reftype( $h ) eq "HASH";

and the method form of C<isa> for the second:

$yes = Foo->isa("Bar");

=cut

X7ROOT File Manager

Editing: UNIVERSAL.pm

Upload File

Create Folder