---
name: "Config::Model::models::Itself::Element"
section: "3pm"
platform: "linux"
package: "libconfig-model-itself-perl"
version: "2.025-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Config::Model::models::Itself::Element"
---

# Config::Model::models::Itself::Element(3pm)

Configuration class Itself::Element

## NAME

Config::Model::models::Itself::Element - Configuration class Itself::Element

## DESCRIPTION

Configuration classes used by Config::Model

## Elements

### type

specify the type of the configuration element.Leaf is used for plain value.  *Mandatory. Type enum. choice: 'node', 'warped\_node', 'hash', 'list', 'leaf', 'check\_list'.*

### value\_type

 *Optional. Type enum. choice: 'boolean', 'enum', 'integer', 'reference', 'number', 'uniline', 'string', 'file', 'dir'.*

Here are some explanations on the possible values:

- 'integer'

  positive or negative integer

- 'uniline'

  string with no embedded newline

### class - Override implementation of element

Perl class name used to override the implementation of the configuration element. This override Perl class must inherit a Config::Model class that matches the element type, i.e. Config::Model::Value, Config::Model::HashId or Config::Model::ListId. Use with care.  *Optional. Type uniline.*

### morph

When set, a recurse copy of the value from the old object to the new object is attempted. Old values are dropped when  a copy is not possible (usually because of mismatching types).  *Optional. Type boolean.*

### refer\_to

points to an array or hash element in the configuration tree using grab syntax. The available choice of this reference value (or check list)is made from the available keys of the pointed hash element or the values of the pointed array element.  *Optional. Type uniline.*

### computed\_refer\_to

points to an array or hash element in the configuration tree using a path computed with value from several other elements in the configuration tree. The available choice of this reference value (or check list) is made from the available keys of the pointed hash element or the values of the pointed array element. The keys of several hashes (or lists) can be combined by using the '+' operator in the formula. For instance, '! host:$a lan + ! host:foobar lan'. See Config::Model::IdElementReference for more details.  *Optional. Type warped\_node.*

### replace\_follow

Path specifying a hash of value element in the configuration tree. The hash if used in a way similar to the replace parameter. In this case, the replacement is not coded in the model but specified by the configuration.  *Optional. Type uniline.*

### compute

compute the default value according to a formula and value from other elements in the configuration tree.  *Optional. Type warped\_node.*

### migrate\_from

Specify an upgrade path from an old value and compute the value to store in the new element.  *Optional. Type warped\_node.*

### write\_as

Specify how to write a boolean value. Example 'no' 'yes'.  *Optional. Type list of uniline.*

### migrate\_values\_from

Specifies that the values of the hash or list are copied from another hash or list in the configuration tree once configuration data are loaded.  *Optional. Type uniline.*

### migrate\_keys\_from

Specifies that the keys of the hash are copied from another hash in the configuration tree only when the hash is created.  *Optional. Type uniline.*

### write\_empty\_value

By default, hash entries without data are not saved in configuration files. Set this parameter to 1 if a key must be saved in the configuration file even if the hash contains no value for that key.  *Optional. Type boolean.*

- upstream\_default value :

  0

### mandatory

 *Optional. Type boolean.*

### config\_class\_name

 *Optional. Type reference.*

### choice

Specify the possible values of an enum. This can also be used in a reference element so the possible enum value will be the combination of the specified choice and the referred to values.  *Optional. Type list of uniline.*

### min

minimum value.  *Optional. Type number.*

### max

maximum value.  *Optional. Type number.*

### min\_index

minimum number of keys.  *Optional. Type integer.*

### max\_index

maximum number of keys.  *Optional. Type integer.*

### default

Specify default value. This default value is written in the configuration data.  *Optional. Type string.*

### upstream\_default

Another way to specify a default value. But this default value is considered as "built\_in" the application and is not written in the configuration data (unless modified)  *Optional. Type string.*

### convert

Convert value or index to uppercase (uc) or lowercase (lc).  *Optional. Type enum.*

### match

Perl regular expression to assert the validity of the value. To check the whole value, use `"^"` and `"$"`. For instance `"^foo|bar$"` allows `"foo"` or `"bar"` but not `"foobar"`. To be case insentive, use the `"(?i)"` extended pattern. For instance, the regexp `"^(?i)foo|bar$"` also allows the values `"Foo"` and `"Bar"`.  *Optional. Type uniline.*

### assert

Raise an error if the test code snippet does returns false. Note this snippet is also run on undefined value, which may not be what you want.  *Optional. Type hash of node of class Itself::CommonElement::Assert .*

### warn\_if

Warn user if the code snippet returns true.  *Optional. Type hash of node of class Itself::CommonElement::Assert .*

### warn\_unless

Warn user if the code snippet returns false.  *Optional. Type hash of node of class Itself::CommonElement::Assert .*

### warn\_if\_match

Warn user if a *defined* value matches the regular expression.  *Optional. Type hash of node of class Itself::CommonElement::WarnIfMatch .*

### warn\_unless\_match

Warn user if *defined* value does not match the regular expression.  *Optional. Type hash of node of class Itself::CommonElement::WarnIfMatch .*

### warn

Unconditionally issue a warning with this string when this parameter is used. This should be used mostly with "accept"  *Optional. Type string.*

### grammar

Feed this grammar to Parse::RecDescent to perform validation.  *Optional. Type string.*

### default\_list

Specify items checked by default.  *Optional. Type check\_list.*

### upstream\_default\_list

Specify items checked by default in the application.  *Optional. Type check\_list.*

### allow\_keys\_from

this hash allows keys from the keys of the hash pointed by the path string.  *Optional. Type uniline.*

### allow\_keys\_matching

Keys must match the specified regular expression.  *Optional. Type uniline.*

### follow\_keys\_from

this hash contains the same keys as the hash pointed by the path string.  *Optional. Type uniline.*

### warn\_if\_key\_match

Warn user if a key is created matching this regular expression.  *Optional. Type uniline.*

### warn\_unless\_key\_match

Warn user if a key is created not matching this regular expression.  *Optional. Type uniline.*

### ordered

keep track of the order of the elements of this hash.  *Optional. Type boolean.*

### default\_keys

default keys hashes.  *Optional. Type list of string.*

### auto\_create\_keys

always create a set of keys specified in this list.  *Optional. Type list of string.*

### allow\_keys

specify a set of allowed keys.  *Optional. Type list of string.*

### auto\_create\_ids

always create the number of id specified in this integer.  *Optional. Type string.*

### default\_with\_init

specify a set of keys to create and initialization on some elements . E.g. ' foo =\> "X=Av Y=Bv", bar =\> "Y=Av Z=Cz"'  *Optional. Type hash of string.*

### max\_nb

 *Optional. Type integer.*

### replace

Used for enum to substitute one value with another. This parameter must be used to enable user to upgrade a configuration with obsolete values. The old value is the key of the hash, the new one is the value of the hash.  *Optional. Type hash of string.*

### duplicates

Specify the policy regarding duplicated values stored in the list or as hash values (valid only when cargo type is "leaf"). The policy can be "allow" (default), "suppress", "warn" (which offers the possibility to apply a fix), "forbid".  *Optional. Type enum. choice: 'allow', 'suppress', 'warn', 'forbid'.*

- upstream\_default value :

  allow

### help

Specify help string applicable to values. The keys are regexp matched to the beginning of the value. See `"help"` parameter of "DESCRIPTION" in Config::Model::Value for more possibilities.  *Optional. Type hash of string.*

### status

 *Optional. Type enum. choice: 'obsolete', 'deprecated', 'standard'.*

- upstream\_default value :

  standard

### level

Used to highlight important parameter or to hide others. Hidden parameter are mostly used to hide features that are unavailable at start time. They can be made available later using warp mechanism.  *Optional. Type enum. choice: 'important', 'normal', 'hidden'.*

- upstream\_default value :

  normal

### summary

enter short information regarding this element.  *Optional. Type uniline.*

### description

enter detailed help information regarding this element.  *Optional. Type string.*

### warp

change the properties (i.e. default value or its value\_type) dynamically according to the value of another Value object located elsewhere in the configuration tree.  *Optional. Type warped\_node of class Itself::WarpValue .*

### index\_type

Specify the type of allowed index for the hash. "String" means no restriction.  *Optional. Type enum.*

### cargo

Specify the properties of the configuration element configuration in this hash or list.  *Optional. Type warped\_node.*

## SEE ALSO

- •

  cme

- •

  Config::Model::models::Itself::CommonElement::Assert

- •

  Config::Model::models::Itself::CommonElement::WarnIfMatch

- •

  Config::Model::models::Itself::WarpValue