Config::Model::WarpedNode - Node that change config class properties
version 2.152
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/} ]
);
}
$model->create_config_class(
name => "MyClass",
element => [
master_switch => {
type => 'leaf',
value_type => 'enum',
choice => [qw/cX cY/]
},
'a_warped_node' => {
type => 'warped_node',
warp => }
follow => { ms => '! master_switch' },
rules => [
'$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
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
"WarpedNode" should not be created directly.
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).
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.
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
Return the name of the node (even if warped out).
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.
Returns the node object hidden behind the warped node. Croaks if the node is not
accessible.
Parameters: "( 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.
$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.
Dominique Dumont, (ddumont at cpan dot org)
Config::Model::Instance, Config::Model, Config::Model::HashId,
Config::Model::ListId, Config::Model::AnyThing, Config::Model::Warper,
Config::Model::WarpedNode, Config::Model::Value
Dominique Dumont
This software is Copyright (c) 2005-2022 by Dominique Dumont.
This is free software, licensed under:
The GNU Lesser General Public License, Version 2.1, February 1999