---
name: "Config::Model::Iterator"
section: "3pm"
platform: "linux"
package: "libconfig-model-perl"
version: "2.155-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Config::Model::Iterator"
---

# Config::Model::Iterator(3pm)

Iterates forward or backward a configuration tree

## NAME

Config::Model::Iterator - Iterates forward or backward a configuration tree

## VERSION

version 2.155

## SYNOPSIS

```
 use Config::Model;
 # define configuration tree object
 my $model = Config::Model->new;
 $model->create_config_class(
    name    => "Foo",
    element => [
        [qw/bar baz/] => {
            type       => 'leaf',
            value_type => 'string',
            level => 'important' ,
        },
    ]
 );
 $model->create_config_class(
    name    => "MyClass",
    element => [
        foo_nodes => {
            type       => 'hash',     # hash id
            index_type => 'string',
            level => 'important' ,
            cargo      => {
                type              => 'node',
                config_class_name => 'Foo'
            },
        },
    ],
 );
 my $inst = $model->instance( root_class_name => 'MyClass' );
 # create some Foo objects
 $inst->config_root->load("foo_nodes:foo1 - foo_nodes:foo2  ") ;
 my $my_leaf_cb = sub {
    my ($iter, $data_r,$node,$element,$index, $leaf_object) = @_ ;
    print "leaf_cb called for ",$leaf_object->location,"\n" ;
 } ;
 my $my_hash_cb = sub {
    my ($iter, $data_r,$node,$element,@keys) = @_ ;
    print "hash_element_cb called for element $element with keys @keys\n" ;
 } ;
 my $iterator = $inst -> iterator (
    leaf_cb         => $my_leaf_cb,
    hash_element_cb => $my_hash_cb ,
 );
 $iterator->start ;
 ### prints
 # hash_element_cb called for element foo_nodes with keys foo1 foo2
 # leaf_cb called for foo_nodes:foo1 bar
 # leaf_cb called for foo_nodes:foo1 baz
 # leaf_cb called for foo_nodes:foo2 bar
 # leaf_cb called for foo_nodes:foo2 baz
```

## DESCRIPTION

This module provides a class that is able to iterate forward or backward a configuration tree. The iterator stops and calls back user defined subroutines on one of the following condition:

- •

  A configuration item contains an error (mostly undefined mandatory values)

- •

  A configuration item contains warnings and the constructor's argument `"call_back_on_warning"` was set.

- •

  A configuration item has a `"important"` level and the constructor's argument `"call_back_on_important"` was set.. See level parameter for details.

The iterator supports going forward and backward (to support `"back"` and `"next"` buttons on a wizard widget).

## CONSTRUCTOR

The constructor should be used only by Config::Model::Instance with the iterator method.

## Creating an iterator

A iterator requires at least two kind of call-back: a call-back for leaf elements and a call-back for hash elements (which is also used for list elements).

These call-back must be passed when creating the iterator (the parameters are named `"leaf_cb"` and `"hash_element_cb"`)

Here are the the parameters accepted by `"iterator"`:

### call\_back\_on\_important

Whether to call back when an important element is found (default 0).

### call\_back\_on\_warning

Whether to call back when an item with warnings is found (default 0).

### status

Specifies the status of the element scanned by the wizard (default 'standard').

### leaf\_cb

Subroutine called backed for leaf elements. See "Callback prototypes" in Config::Model::ObjTreeScanner for signature and details. (mandatory)

### hash\_element\_cb

Subroutine called backed for hash elements. See "Callback prototypes" in Config::Model::ObjTreeScanner for signature and details. (mandatory)

## Custom callbacks

By default, `"leaf_cb"` is called for all types of leaf elements (i.e enum. integer, strings, ...). But you can provide dedicated call-back for each type of leaf:

```
 enum_value_cb, integer_value_cb, number_value_cb, boolean_value_cb,
 uniline_value_cb, string_value_cb
```

Likewise, you can also provide a call-back dedicated to list elements with `"list_element_cb"`

## Methods

### start

Start the scan and perform call-back when needed. This function returns when the scan is completely done.

### bail\_out

When called, a variable is set so that all call\_backs returns as soon as possible. Used to abort wizard.

### go\_forward

Set wizard in forward (default) mode.

### go\_backward

Set wizard in backward mode.

## AUTHOR

Dominique Dumont, (ddumont at cpan dot org)

## SEE ALSO

Config::Model, Config::Model::Instance, Config::Model::Node, Config::Model::HashId, Config::Model::ListId, Config::Model::Value, Config::Model::CheckList, Config::Model::ObjTreeScanner,

## 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
```