Provided by: libconfig-model-perl_2.117-1_all 
NAME
Config::Model::WarpedNode - Node that change config class properties
VERSION
version 2.117
SYNOPSIS
use Config::Model;
my $model = Config::Model->new;
foreach (qw/X Y/) {
$model->create_config_class(
name => "Class$_",
element => [ foo => {qw/type leaf value_type string/} ]
);
}
$model->create_config_class(
name => "MyClass",
element => [
master_switch => {
type => 'leaf',
value_type => 'enum',
choice => [qw/cX cY/]
},
'a_warped_node' => {
type => 'warped_node',
follow => { ms => '! master_switch' },
rules => [
'$ms eq "cX"' => { config_class_name => 'ClassX' },
'$ms eq "cY"' => { config_class_name => 'ClassY' },
]
},
],
);
my $inst = $model->instance(root_class_name => 'MyClass' );
my $root = $inst->config_root ;
print "Visible elements: ",join(' ',$root->get_element_name),"\n" ;
# Visible elements: master_switch
$root->load( steps => 'master_switch=cX' );
print "Visible elements: ",join(' ',$root->get_element_name),"\n" ;
# Visible elements: master_switch a_warped_node
my $node = $root->grab('a_warped_node') ;
print "a_warped_node class: ",$node->config_class_name,"\n" ;
# a_warped_node class: ClassX
$root->load( steps => 'master_switch=cY' );
print "a_warped_node class: ",$node->config_class_name,"\n" ;
# a_warped_node class: ClassY
DESCRIPTION
This class provides a way to change dynamically the configuration class (or some other
properties) of a node. The changes are done according to the model declaration.
This declaration specifies one (or several) leaf in the configuration tree that triggers
the actual property change of the warped node. This leaf is also referred as warp master.
When the warp master(s) value(s) changes, "WarpedNode" creates an instance of the new
class required by the warp master.
If the morph parameter is set, the values held by the old object are (if possible) copied
to the new instance of the object using copy_from method.
Warped node can alter the following properties:
config_class_name
level
Constructor
"WarpedNode" should not be created directly.
Warped node model declaration
Parameter overview
A warped node must be declared with the following parameters:
type
Always set to "warped_node".
follow
Grab string leading to the "Config::Model::Value" warp master. See "Warp follow
argument" in Config::Model::Warper for details.
morph
boolean. If 1, "WarpedNode" tries to recursively copy the value from the old object to
the new object using copy_from method. When a copy is not possible, undef values are
assigned to object elements.
rules
Hash or array ref that specify the property change rules according to the warp
master(s) value(s). See "Warp rules argument" in Config::Model::Warper for details on
how to specify the warp master values (or combination of values).
Effect declaration
For a warped node, the effects are declared with these parameters:
config_class_name
When requested by the warp master,the "WarpedNode" creates a new object of the
type specified by this parameter:
XZ => { config_class_name => 'SlaveZ' }
Instead of a string, you can an array ref which contains the class name and
constructor arguments :
XY => { config_class_name => ['SlaveY', foo => 'bar' ], },
class Specify a Perl class to implement the above config class. This Perl Class must
inherit Config::Model::Node.
Forwarded methods
The following methods are forwarded to contained node:
fetch_element config_class_name get_element_name has_element is_element_available
element_type load fetch_element_value get_type get_cargo_type describe
Methods
name
Return the name of the node (even if warped out).
is_accessible
Returns true if the node hidden behind this warped node is accessible, i.e. the warp
master have values so a node was warped in.
get_actual_node
Returns the node object hidden behind the warped node. Croaks if the node is not
accessible.
load_data ( hash_ref )
Load configuration data with a hash ref. The hash ref key must match the available
elements of the node carried by the warped node.
EXAMPLE
$model ->create_config_class
(
element =>
[
tree_macro => { type => 'leaf',
value_type => 'enum',
choice => [qw/XX XY XZ ZZ/]
},
bar => {
type => 'warped_node',
follow => '! tree_macro',
morph => 1,
rules => [
XX => { config_class_name
=> [ 'ClassX', 'foo' ,'bar' ]}
XY => { config_class_name => 'ClassY'},
XZ => { config_class_name => 'ClassZ'}
]
}
]
);
In the example above we see that:
• The 'bar' slot can refer to a "ClassX", "ClassZ" or "ClassY" object.
• The warper object is the "tree_macro" attribute of the root of the object tree.
• When "tree_macro" is set to "ZZ", "bar" is not available. Trying to access "bar"
raises an exception.
• When "tree_macro" is changed from "ZZ" to "XX", "bar" refers to a brand new "ClassX"
object constructed with "ClassX->new(foo => 'bar')"
• Then, if "tree_macro" is changed from "XX" to "XY", "bar" refers to a brand new
"ClassY" object. But in this case, the object is initialized with most if not all the
attributes of "ClassX". This copy is done whenever "tree_macro" is changed.
AUTHOR
Dominique Dumont, (ddumont at cpan dot org)
SEE ALSO
Config::Model::Instance, Config::Model, Config::Model::HashId, Config::Model::ListId,
Config::Model::AnyThing, Config::Model::Warper, Config::Model::WarpedNode,
Config::Model::Value
AUTHOR
Dominique Dumont
COPYRIGHT AND LICENSE
This software is Copyright (c) 2005-2018 by Dominique Dumont.
This is free software, licensed under:
The GNU Lesser General Public License, Version 2.1, February 1999