Object::Pad::MetaFunctUser(Contributed Perl DocObject::Pad::MetaFunctions(3pm)
NAME
"Object::Pad::MetaFunctions" - utility functions for "Object::Pad"
classes
SYNOPSIS
use v5.36;
use Object::Pad::MetaFunctions qw( deconstruct_object );
sub debug_print_object ( $obj )
{
my ( $classname, @repr ) = deconstruct_object( $obj );
say "An object of type $classname having:";
foreach my ( $fieldname, $value ) ( @repr ) {
printf "%30s = %s\n", $fieldname, $value;
}
}
DESCRIPTION
This module contains a number of miscellaneous utility functions for
working with Object::Pad-based classes or instances thereof.
These functions all involve a certain amount of encapsulation-breaking
into the object instances being operated on. This sort of thing
shouldn't be encouraged in most regular code, but there can be
occasions when it is useful; such as debug printing of values, generic
serialisation, or tightly-coupled unit tests that wish to operate on
the interals of the object instances they test.
Therefore, use of these functions should be considered "last-resort".
Consider carefully the sorts of things you are trying to do with them,
and whether this kind of reaching into the internals of an object,
bypassing all of its interface encapsulation, is really the best
technique to achieve your goal.
FUNCTIONS
metaclass
$metaclass = metaclass( $obj )
Since version 0.67.
Returns the Object::Pad::MOP::Class metaclass associated with the class
that the object is an instance of.
deconstruct_object
( $classname, @repr ) = deconstruct_object( $obj )
Since version 0.67.
Returns a list of perl values containing a representation of all the
fields in the object instance. This representation form may be useful
for tasks such as debug printing or serialisation of the instance. This
list is prefixed by the name of the class of instance as a plain
string.
The exact form of this representation is still experimental and may
change in a later version. Currently, it takes the form of an even-
sized list of key/value pairs, associating field names with their
values. Each key gives the name of a component class and the full name
of the field within it, separated by a dot (".").
'CLASSNAME.$FIELD1' => VALUE, 'CLASSNAME.@FIELD2' => VALUE, ...
In the case of scalar fields, the value is the actual value of that
field. In the case of array or hash fields, the value in the repr list
is a reference to an anonymous copy of the value stored in the field.
'CLASSNAME.$SCALARFIELD' => $VALUE,
'CLASSNAME.@ARRAYFIELD' => [ @VALUE ],
'CLASSNAME.%HASHFIELD' => { %VALUE },
The pairs are ordered, with the actual object class type first,
followed by any roles added by that class, then each parent class
recursively. Within each component class, the fields are given in
declared order.
This reliable ordering may be useful when printing values in human-
readable form, or serialising to some stable storage.
ref_field
$fieldref = ref_field( $fieldname, $obj )
Since version 0.67.
Returns a reference to the named field storage variable of the given
instance object. The $fieldname should be specified as the class name
and the field name separated by a dot (".") (as per
"deconstruct_object").
The class name may also be omitted; at which point the first occurance
of a field of the given name found in any component class it matched
instead.
If no matching field is found, an exception is thrown.
Be careful when using this function as it has the ability to expose
instance fields in a way that allows them to be modified. For a safer
alternative when only read access is required, use "get_field" instead.
get_field
$scalar = get_field( $fieldname, $obj )
@array = get_field( $fieldname, $obj )
%hash = get_field( $fieldname, $obj )
Since version 0.67.
Returns the value of the named field of the given instance object.
Behaves correctly given context; namely, that when invoked on array or
hash fields in scalar context it will return the number of elements or
keys, or in list context will return the list of elements or key/value
pairs.
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.36.0 2023-01-13 Object::Pad::MetaFunctions(3pm)
Generated by dwww version 1.15 on Tue Jun 25 02:23:34 CEST 2024.