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

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NAME

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

VERSION

version 2.106

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');

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 element 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.

xxx:yy

Go down using "xxx" element and id "yy" (valid for hash or list elements)

?xxx

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

If "?xxx:yy", go up the tree the same way. But no check is done to see if id "yy" 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) 2005-2017 by Dominique Dumont.

This is free software, licensed under:

  The GNU Lesser General Public License, Version 2.1, February 1999