Config::Model::Role::Grab(3pm)

NAME
Config::Model::Role::Grab - Role to grab data from elsewhere in the tree

VERSION
version 2.165

SYNOPSIS
  $root->grab('foo:2 bar');
  $root->grab(steps => 'foo:2 bar');
  $root->grab(steps => 'foo:2 bar', type => 'leaf');
  $root->grab_value(steps => 'foo:2 bar');
  $root->grab_value(steps => '"a.string"'); # contains . in name -> quote

DESCRIPTION
Role used to let a tree item (i.e. node, hash, list or leaf) to grab another item or value from the configuration tree using a path (a bit like an xpath path with a different syntax).

METHODS

  grab
Grab an object from the configuration tree.

Parameters are:

"steps" (or "step")
    A string indicating the steps to follow in the tree to find the required item. (mandatory)

"mode"
    When set to "strict", "grab" throws an exception if no object is found using the passed string. When set to "adaptative", the object found last is returned. For instance, for the steps "good_step wrong_step", only the object held by "good_step" is returned. When set to "loose", grab returns undef in case of problem. (default is "strict")

"type"
    Either "node", "leaf", "hash" or "list" or an array ref containing these values. Returns only an object of requested type. Depending on "strict" value, "grab" either throws an exception or returns the last object found with the requested type. (optional, default to "undef", which means any type of object)

    Examples:

     $root->grab(steps => 'foo:2 bar', type => 'leaf')
     $root->grab(steps => 'foo:2 bar', type => ['leaf','check_list'])

"autoadd"
    When set to 1, "hash" or "list" configuration elements are created when requested by the passed steps. (default is 1).

grab_non_available
    When set to 1, "grab" returns an object even if this one is not available. I.e. even if this element was warped out. (default is 0).

The "steps" parameters is made of the following items separated by spaces:

-   Go up one node

!   Go to the root node.

!Foo
    Go up the configuration tree until the "Foo" configuration class is found. Raise an exception if no "Foo" class is found when root node is reached.

xxx Go down using "xxx" element. Quotes must be used if element name is not alphanumeric.

xxx:yy
    Go down using "xxx" element and id "yy" (valid for hash or list elements).
     Quotes must be used if id is not alphanumeric.

?xxx
    Go up the tree until a node containing element "xxx" is found. Then go down the tree like item "xxx".

    "?xxx:yy" goes up the tree the same way. But no check is done to see if id "yy" key actually exists or not. Only the element "xxx" is considered when going up the tree.

  grab_value
Like "grab", but returns the value of a leaf or check_list object, not just the leaf object.

"grab_value" raises an exception if following the steps ends on anything but a leaf or a check_list.

  grab_annotation
Like "grab", but returns the annotation of an object.

  grab_root
Returns the root of the configuration tree.

  grab_ancestor
Parameter: a configuration class name

Go up the configuration tree until a node using the configuration class is found. Returns the found node or undef.

Example:

  # returns a Config::Model::Node object for a Systemd::Service config class
  $self->grab('Systemd::Service');

AUTHOR
Dominique Dumont

COPYRIGHT AND LICENSE
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