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.\" ========================================================================
.\"
.IX Title "Config::Model::WarpedNode 3pm"
.TH Config::Model::WarpedNode 3pm "2023-08-19" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Config::Model::WarpedNode \- Node that change config class properties
.SH "VERSION"
.IX Header "VERSION"
version 2.153
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& 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/} ]
\&    );
\& }
\& $model\->create_config_class(
\&    name => "MyClass",
\&
\&    element => [
\&        master_switch => {
\&            type       => \*(Aqleaf\*(Aq,
\&            value_type => \*(Aqenum\*(Aq,
\&            choice     => [qw/cX cY/]
\&        },
\&
\&        \*(Aqa_warped_node\*(Aq => {
\&            type   => \*(Aqwarped_node\*(Aq,
\&            warp => }
\&               follow => { ms => \*(Aq! master_switch\*(Aq },
\&               rules  => [
\&                   \*(Aq$ms eq "cX"\*(Aq => { config_class_name => \*(AqClassX\*(Aq },
\&                   \*(Aq$ms eq "cY"\*(Aq => { config_class_name => \*(AqClassY\*(Aq },
\&               ]
\&            }
\&        },
\&    ],
\& );
\&
\& my $inst = $model\->instance(root_class_name => \*(AqMyClass\*(Aq );
\& my $root = $inst\->config_root ;
\&
\& print "Visible elements: ",join(\*(Aq \*(Aq,$root\->get_element_name),"\en" ;
\& # Visible elements: master_switch
\&
\& $root\->load( steps => \*(Aqmaster_switch=cX\*(Aq );
\& print "Visible elements: ",join(\*(Aq \*(Aq,$root\->get_element_name),"\en" ;
\& # Visible elements: master_switch a_warped_node
\&
\& my $node = $root\->grab(\*(Aqa_warped_node\*(Aq) ;
\& print "a_warped_node class: ",$node\->config_class_name,"\en" ;
\& # a_warped_node class: ClassX
\&
\& $root\->load( steps => \*(Aqmaster_switch=cY\*(Aq );
\& print "a_warped_node class: ",$node\->config_class_name,"\en" ;
\& # a_warped_node class: ClassY
.Ve
.SH "DESCRIPTION"
.IX Header "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.
.PP
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 \fIwarp master\fR.
.PP
When the warp master(s) value(s) changes, \f(CW\*(C`WarpedNode\*(C'\fR creates an instance
of the new class required by the warp master.
.PP
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.
.PP
Warped node can alter the following properties:
.PP
.Vb 2
\& config_class_name
\& level
.Ve
.SH "Constructor"
.IX Header "Constructor"
\&\f(CW\*(C`WarpedNode\*(C'\fR should not be created directly.
.SH "Warped node model declaration"
.IX Header "Warped node model declaration"
.SS "Parameter overview"
.IX Subsection "Parameter overview"
A warped node must be declared with the following parameters:
.IP "type" 4
.IX Item "type"
Always set to \f(CW\*(C`warped_node\*(C'\fR.
.IP "follow" 4
.IX Item "follow"
Grab string leading to the
\&\f(CW\*(C`Config::Model::Value\*(C'\fR warp master.
See \*(L"Warp follow argument\*(R" in Config::Model::Warper for details.
.IP "morph" 4
.IX Item "morph"
boolean. If 1, \f(CW\*(C`WarpedNode\*(C'\fR 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.
.IP "rules" 4
.IX Item "rules"
Hash or array ref that specify the property change rules according to the
warp master(s) value(s). 
See \*(L"Warp rules argument\*(R" in Config::Model::Warper for details 
on how to specify the warp master values (or combination of values).
.SS "Effect declaration"
.IX Subsection "Effect declaration"
For a warped node, the effects are declared with these parameters:
.IP "\fBconfig_class_name\fR" 8
.IX Item "config_class_name"
When requested by the warp master,the \f(CW\*(C`WarpedNode\*(C'\fR creates a new
object of the type specified by this parameter:
.Sp
.Vb 1
\&  XZ => { config_class_name => \*(AqSlaveZ\*(Aq }
.Ve
.Sp
Instead of a string, you can an array ref which contains the class
name and constructor arguments :
.Sp
.Vb 1
\&  XY  => { config_class_name => [\*(AqSlaveY\*(Aq, foo => \*(Aqbar\*(Aq ], },
.Ve
.IP "\fBclass\fR" 8
.IX Item "class"
Specify a Perl class to implement the above config class. This Perl Class \fBmust\fR inherit
Config::Model::Node.
.SH "Forwarded methods"
.IX Header "Forwarded methods"
The following methods are forwarded to contained node:
.PP
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
.SH "Methods"
.IX Header "Methods"
.SS "name"
.IX Subsection "name"
Return the name of the node (even if warped out).
.SS "is_accessible"
.IX Subsection "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.
.SS "get_actual_node"
.IX Subsection "get_actual_node"
Returns the node object hidden behind the warped node. Croaks if the
node is not accessible.
.SS "load_data"
.IX Subsection "load_data"
Parameters: \f(CW\*(C`( hash_ref )\*(C'\fR
.PP
Load configuration data with a hash ref. The hash ref key must match
the available elements of the node carried by the warped node.
.SH "EXAMPLE"
.IX Header "EXAMPLE"
.Vb 10
\& $model \->create_config_class 
\&  (
\&   element =>
\&    [
\&     tree_macro => { type => \*(Aqleaf\*(Aq,
\&                     value_type => \*(Aqenum\*(Aq,
\&                     choice     => [qw/XX XY XZ ZZ/]
\&                   },
\&     bar =>  {
\&               type => \*(Aqwarped_node\*(Aq,
\&               follow => \*(Aq! tree_macro\*(Aq, 
\&               morph => 1,
\&               rules => [
\&                         XX => { config_class_name 
\&                                   => [ \*(AqClassX\*(Aq, \*(Aqfoo\*(Aq ,\*(Aqbar\*(Aq ]}
\&                         XY => { config_class_name => \*(AqClassY\*(Aq},
\&                         XZ => { config_class_name => \*(AqClassZ\*(Aq}
\&                        ]
\&             }
\&    ]
\&  );
.Ve
.PP
In the example above we see that:
.IP "\(bu" 4
The 'bar' slot can refer to a \f(CW\*(C`ClassX\*(C'\fR, \f(CW\*(C`ClassZ\*(C'\fR or \f(CW\*(C`ClassY\*(C'\fR object.
.IP "\(bu" 4
The warper object is the \f(CW\*(C`tree_macro\*(C'\fR attribute of the root of the
object tree.
.IP "\(bu" 4
When \f(CW\*(C`tree_macro\*(C'\fR is set to \f(CW\*(C`ZZ\*(C'\fR, \f(CW\*(C`bar\*(C'\fR is not available. Trying to
access \f(CW\*(C`bar\*(C'\fR raises an exception.
.IP "\(bu" 4
When \f(CW\*(C`tree_macro\*(C'\fR is changed from \f(CW\*(C`ZZ\*(C'\fR to \f(CW\*(C`XX\*(C'\fR, 
\&\f(CW\*(C`bar\*(C'\fR refers to a brand new \f(CW\*(C`ClassX\*(C'\fR
object constructed with \f(CW\*(C`ClassX\->new(foo => \*(Aqbar\*(Aq)\*(C'\fR
.IP "\(bu" 4
Then, if \f(CW\*(C`tree_macro\*(C'\fR is changed from \f(CW\*(C`XX\*(C'\fR to \f(CW\*(C`XY\*(C'\fR, \f(CW\*(C`bar\*(C'\fR
refers to a brand new \f(CW\*(C`ClassY\*(C'\fR object. But in this case, the object is
initialized with most if not all the attributes of \f(CW\*(C`ClassX\*(C'\fR. This copy
is done whenever \f(CW\*(C`tree_macro\*(C'\fR is changed.
.SH "AUTHOR"
.IX Header "AUTHOR"
Dominique Dumont, (ddumont at cpan dot org)
.SH "SEE ALSO"
.IX Header "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
.SH "AUTHOR"
.IX Header "AUTHOR"
Dominique Dumont
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is Copyright (c) 2005\-2022 by Dominique Dumont.
.PP
This is free software, licensed under:
.PP
.Vb 1
\&  The GNU Lesser General Public License, Version 2.1, February 1999
.Ve