Config::Model::Warper

Warp follow argument

Grab string leading to the "Config::Model::Value" or Config::Model::CheckList 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' }

Note: By design "follow" argument of warper module is a plain path to keep warp mechanism (relatively) simple. "follow" argument of Config::Model::ValueComputer has more features and is documented there

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 when macro1 is A> },
            B => { <effect when macro1 is 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.

The rules must be declared with a slightly different way when a check_list is used as a warp master: a check_list has not a simple value. The rule must check whether a value is checked or not amongs all the possible items of a check list.

For example, let's say that $cl in the rule below point to a check list whose items are "A" and "B". The rule must verify if the item is set or not:

  rules => [
       '$cl.is_set(A)' =>  { <effect when A is set> },
       '$cl.is_set(B)' =>  { <effect when B is set> },
       # can be combined
       '$cl.is_set(B) and $cl.is_set(A)' =>  { <effect when A and B are set> },
   ],

With this feature, you can control with a check list whether some element must be shown or not (assuming "FooClass" and "BarClass" classes are declared):

    element => [
        # warp master
        my_check_list => {
            type       => 'check_list',
            choice     => ['has_foo','has_bar']
        },
        # controlled element that show up only when has_foo is set
        foo => {
            type => 'warped_node',
            level => 'hidden',
            config_class_name => 'FooClass',
            follow => {
                selected => '- my_check_list'
            },
            'rules' => [
                '$selected.is_set(has_foo)' => {
                    level => 'normal'
                }
            ]
        },
        # controlled element that show up only when has_bar is set
        bar => {
            type => 'warped_node',
            level => 'hidden',
            config_class_name => 'BarClass',
            follow => {
                selected => '- my_check_list'
            },
            'rules' => [
                '$selected.is_set(has_bar)' => {
                    level => 'normal'
                }
            ]
        }
    ]

warp_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)