Warp follow argument

 follow => '! tree_macro'

In case of several warp master, "follow" is 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

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 is 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 is sanitized and used in a Perl eval, so you can use most Perl syntax and regular expressions.

Functions (like &foo) are 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

• 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)