Config::Model::WarpedTUser(Contributed Perl DocumConfig::Model::WarpedThing(3)NAMEConfig::Model::WarpedThing - Base class for warped classes
VERSION
version 1.235
SYNOPSIS
# internal class
DESCRIPTION
This class must be inherited by all classes that can be warped by
Config::Model::Value. This class provides a set of methods that are
expected by a warp master from a warped class.
Currently this class is inherited by Config::Model::Value,
Config::Model::AnyId and Config::Model::WarpedNode.
WarpThing does not provide a constructor.
Warper and warped
Warping an object means that the properties of the object will be
changed depending on the value of another object.
The changed object is referred as the warped object.
The other object that holds the important value is referred as the warp
master or the warper object.
You can also set up several warp master for one warped object. This
means that the properties of the warped object will be changed
according to a combination of values of the warp masters.
Warp arguments
Warp arguments are passed in a hash ref whose keys are "follow" and and
"rules":
Warp follow argument
Grab string leading to the "Config::Model::Value" warp master. E.g.:
follow => '! tree_macro'
In case of several warp master, "follow" will be set to an array ref of
several grab string:
follow => [ '! macro1', '- macro2' ]
You can also use named parameters:
follow => { m1 => '! macro1', m2 => '- macro2' }
Warp rules argument
String, hash ref or array ref that specify the warped object property
changes. These rules specifies the actual property changes for the
warped object depending on the value(s) of the warp master(s).
E.g. for a simple case (rules is a hash ref) :
follow => '! macro1' ,
rules => { A => { <effect for macro1 == A> },
B => { <effect for macro1 == B> }
}
In case of similar effects, you can use named parameters and a boolean
expression to specify the effect. The first match will be applied. In
this case, rules is a list ref:
follow => { m => '! macro1' } ,
rules => [ '$m eq "A"' => { <effect for macro1 == A> },
'$m eq "B" or $m eq"C "' => { <effect for macro1 == B|C > }
]
In case of several warp masters, "follow" must use named parameters,
and rules must use boolean expression:
follow => { m1 => '! macro1', m2 => '- macro2' } ,
rules => [
'$m1 eq "A" && $m2 eq "C"' => { <effect for A C> },
'$m1 eq "A" && $m2 eq "D"' => { <effect for A D> },
'$m1 eq "B" && $m2 eq "C"' => { <effect for B C> },
'$m1 eq "B" && $m2 eq "D"' => { <effect for B D> },
]
Of course some combinations of warp master values can have the same
effect:
follow => { m1 => '! macro1', m2 => '- macro2' } ,
rules => [
'$m1 eq "A" && $m2 eq "C"' => { <effect X> },
'$m1 eq "A" && $m2 eq "D"' => { <effect Y> },
'$m1 eq "B" && $m2 eq "C"' => { <effect Y> },
'$m1 eq "B" && $m2 eq "D"' => { <effect Y> },
]
In this case, you can use different boolean expression to save typing:
follow => { m1 => '! macro1', m2 => '- macro2' } ,
rules => [
'$m1 eq "A" && $m2 eq "C"' => { <effect X> },
'$m1 eq "A" && $m2 eq "D"' => { <effect Y> },
'$m1 eq "B" && ( $m2 eq "C" or $m2 eq "D") ' => { <effect Y> },
]
Note that the boolean expression will be sanitized and used in a Perl
eval, so you can use most Perl syntax and regular expressions.
Function (like &foo) will be called like "$self->foo" before
evaluation\ of the boolean expression.
Methodswarp_error()
This method returns a string describing:
· The location(s) of the warp master
· The current value(s) of the warp master(s)
· The other values accepted by the warp master that can be tried (if
the warp master is an enumerated type)
How does this work ?
Registration
· When a warped object is created, the constructor will register
to the warp masters. The warp master are found by using the
special string passed to the "follow" parameter. As explained
in grab method, the string provides the location of the warp
master in the configuration tree using a symbolic form.
· Then the warped object retrieve the value(s) of the warp
master(s)
· Then the warped object warps itself using the above value(s).
Depending on these value(s), the properties of the warped
object will be modified.
Master update
· When a warp master value is updated, the warp master will call
all its warped object and pass them the new master value.
· Then each warped object will modify its properties according to
the new warp master value.
AUTHOR
Dominique Dumont, (ddumont at cpan dot org)
SEE ALSO
Config::Model::AnyThing, Config::Model::HashId, Config::Model::ListId,
Config::Model::WarpedNode, Config::Model::Value
perl v5.14.1 2011-07-22 Config::Model::WarpedThing(3)
