#

API Docs for: 3.10.3
Show: Inherited Protected Private Deprecated

# BaseCore Class

Uses

- AttributeCore

Defined in: `base/js/BaseCore.js:43`
Module: base-core
Parent Module: base

The BaseCore class, is the lightest version of Base, and provides Base's basic lifecycle management and ATTRS construction support, but doesn't fire init/destroy or attribute change events.

BaseCore also handles the chaining of initializer and destructor methods across the hierarchy as part of object construction and destruction. Additionally, attributes configured through the static ATTRS property for each class in the hierarchy will be initialized by BaseCore.

Classes which require attribute support, but don't intend to use/expose attribute change events can extend BaseCore instead of Base for optimal kweight and runtime performance.

## Constructor

### `BaseCore`

(

- `cfg`

)

Defined in `base/js/BaseCore.js:43`

#### Parameters:

- `cfg` Object

  Object with configuration property name/value pairs. The object can be used to provide initial values for the objects published attributes.

- Index
- Methods
- Properties
- Attributes

## Item Index

### Methods

- _addAttrs
- _addLazyAttr
- _aggregateAttrs
- _attrCfgHash
- _baseDestroy
- _baseInit
- _cloneDefaultValue
- _destroyHierarchy
- _filterAdHocAttrs
- _filterAttrCfgs
- _getAttr
- _getAttrCfgs
- _getAttrInitVal
- _getAttrs
- _getClasses
- _getStateVal
- _initAttrHost
- _initAttribute
- _initAttrs
- _initBase
- _initHierarchy
- _initHierarchyData
- _isLazyAttr
- _normAttrVals
- _protectAttrs deprecated
- _set
- _setAttr
- _setAttrs
- _setAttrVal
- _setStateVal
- addAttr
- addAttrs
- attrAdded
- destroy
- get
- getAttrs
- init
- modifyAttrs static
- set
- setAttrs
- toString

### Properties

- _allowAdHocAttrs
- _ATTR_CFG static
- _NON_ATTRS_CFG static
- ATTRS static
- NAME static
- name deprecated

### Attributes

- destroyed
- initialized

## Methods

### `_addAttrs`

(

- `cfgs`
- `values`
- `lazy`

)
private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:836`

Implementation behind the public addAttrs method.

This method is invoked directly by get if it encounters a scenario in which an attribute's valueFn attempts to obtain the value an attribute in the same group of attributes, which has not yet been added (on demand initialization).

#### Parameters:

- `cfgs` Object

  An object with attribute name/configuration pairs.

- `values` Object

  An object with attribute name/value pairs, defining the initial values to apply. Values defined in the cfgs argument will be over-written by values in this argument unless defined as read only.

- `lazy` Boolean

  Whether or not to delay the intialization of these attributes until the first call to get/set. Individual attributes can over-ride this behavior by defining a lazyAdd configuration property in their configuration. See addAttr.

### `_addLazyAttr`

(

- `name`
- `[lazyCfg]`

)
private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:382`

Finishes initializing an attribute which has been lazily added.

#### Parameters:

- `name` Object

  The name of the attribute

- `[lazyCfg]` Object optional

  Optional config hash for the attribute. This is added for performance along the critical path, where the calling method has already obtained lazy config from state.

### `_aggregateAttrs`

(

- `allAttrs`

)
Object private

Defined in `base/js/BaseCore.js:575`

A helper method, used by _initHierarchyData to aggregate attribute configuration across the instances class hierarchy.

The method will protect the attribute configuration value to protect the statically defined default value in ATTRS if required (if the value is an object literal, array or the attribute configuration has cloneDefaultValue set to shallow or deep).

#### Parameters:

- `allAttrs` Array

  An array of ATTRS definitions across classes in the hierarchy (subclass first, Base last)

#### Returns:

Object: The aggregate set of ATTRS definitions for the instance

### `_attrCfgHash`

() private

Defined in `base/js/BaseCore.js:538`

Utility method to define the attribute hash used to filter/whitelist property mixes for this class for iteration performance reasons.

### `_baseDestroy`

() private

Defined in `base/js/BaseCore.js:309`

Internal destroy implementation for BaseCore

### `_baseInit`

() private

Defined in `base/js/BaseCore.js:281`

Internal initialization implementation for BaseCore

### `_cloneDefaultValue`

(

- `cfg`

)
private

Defined in `base/js/BaseCore.js:549`

This method assumes that the value has already been checked to be an object. Since it's on a critical path, we don't want to re-do the check.

#### Parameters:

- `cfg` Object

### `_destroyHierarchy`

() private

Defined in `base/js/BaseCore.js:721`

Destroys the class hierarchy for this instance by invoking the destructor method on the prototype of each class in the hierarchy.

### `_filterAdHocAttrs`

(

- `allAttrs`
- `userVals`

)
Object private

Defined in `base/js/BaseCore.js:427`

#### Parameters:

- `allAttrs` Object

  The set of all attribute configurations for this instance. Attributes will be removed from this set, if they belong to the filtered class, so that by the time all classes are processed, allCfgs will be empty.

- `userVals` Object

  The config object passed in by the user, from which adhoc attrs are to be filtered.

#### Returns:

Object: The set of adhoc attributes passed in, in the form of an object with attribute name/configuration pairs.

### `_filterAttrCfgs`

(

- `clazz`
- `allCfgs`

)
Object private

Defined in `base/js/BaseCore.js:356`

A helper method used when processing ATTRS across the class hierarchy during initialization. Returns a disposable object with the attributes defined for the provided class, extracted from the set of all attributes passed in.

#### Parameters:

- `clazz` Function

  The class for which the desired attributes are required.

- `allCfgs` Object

  The set of all attribute configurations for this instance. Attributes will be removed from this set, if they belong to the filtered class, so that by the time all classes are processed, allCfgs will be empty.

#### Returns:

Object: The set of attributes belonging to the class passed in, in the form of an object with attribute name/configuration pairs.

### `_getAttr`

(

- `name`

)
Any protected chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:543`

Provides the common implementation for the public get method, allowing Attribute hosts to over-ride either method.

See get for argument details.

#### Parameters:

- `name` String

  The name of the attribute.

#### Returns:

Any: The value of the attribute.

### `_getAttrCfgs`

() Object protected

Defined in `base/js/BaseCore.js:339`

Returns an aggregated set of attribute configurations, by traversing the class hierarchy.

#### Returns:

Object: The hash of attribute configurations, aggregated across classes in the hierarchy This value is cached the first time the method, or _getClasses, is invoked. Subsequent invocations return the cached value.

### `_getAttrInitVal`

(

- `attr`
- `cfg`
- `initValues`

)
Any private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:945`

Returns the initial value of the given attribute from either the default configuration provided, or the over-ridden value if it exists in the set of initValues provided and the attribute is not read-only.

#### Parameters:

- `attr` String

  The name of the attribute

- `cfg` Object

  The attribute configuration object

- `initValues` Object

  The object with simple and complex attribute name/value pairs returned from _normAttrVals

#### Returns:

Any: The initial value of the attribute.

### `_getAttrs`

(

- `attrs`

)
Object protected

Inherited from AttributeCore: `attribute/js/AttributeCore.js:774`

Implementation behind the public getAttrs method, to get multiple attribute values.

#### Parameters:

- `attrs` Array | boolean

  Optional. An array of attribute names. If omitted, all attribute values are returned. If set to true, all attributes modified from their initial values are returned.

#### Returns:

Object: An object with attribute name/value pairs.

### `_getClasses`

() Function[] protected

Defined in `base/js/BaseCore.js:323`

Returns the class hierarchy for this object, with BaseCore being the last class in the array.

#### Returns:

Function[]: An array of classes (constructor functions), making up the class hierarchy for this object. This value is cached the first time the method, or _getAttrCfgs, is invoked. Subsequent invocations return the cached value.

### `_getStateVal`

(

- `name`
- `[cfg]`

)
Any private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:600`

Gets the stored value for the attribute, from either the internal state object, or the state proxy if it exits

#### Parameters:

- `name` String

  The name of the attribute

- `[cfg]` Object optional

  Optional config hash for the attribute. This is added for performance along the critical path, where the calling method has already obtained the config from state.

#### Returns:

Any: The stored value of the attribute

### `_initAttrHost`

(

- `attrs`
- `values`
- `lazy`

)
private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:140`

Constructor logic for attributes. Initializes the host state, and sets up the inital attributes passed to the constructor.

#### Parameters:

- `attrs` Object

  The attributes to add during construction (passed through to addAttrs). These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.

- `values` Object

  The initial attribute values to apply (passed through to addAttrs). These are not merged/cloned. The caller is responsible for isolating user provided values if required.

- `lazy` Boolean

  Whether or not to add attributes lazily (passed through to addAttrs).

### `_initAttribute`

() private

Defined in `base/js/BaseCore.js:254`

Initializes AttributeCore

### `_initAttrs`

(

- `attrs`
- `values`
- `lazy`

)
protected

Inherited from AttributeCore: `attribute/js/AttributeCore.js:1011`

Utility method to set up initial attributes defined during construction, either through the constructor.ATTRS property, or explicitly passed in.

#### Parameters:

- `attrs` Object

  The attributes to add during construction (passed through to addAttrs). These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.

- `values` Object

  The initial attribute values to apply (passed through to addAttrs). These are not merged/cloned. The caller is responsible for isolating user provided values if required.

- `lazy` Boolean

  Whether or not to add attributes lazily (passed through to addAttrs).

### `_initBase`

(

- `config`

)
private

Defined in `base/js/BaseCore.js:219`

Internal construction logic for BaseCore.

#### Parameters:

- `config` Object

  The constructor configuration object

### `_initHierarchy`

(

- `userVals`

)
private

Defined in `base/js/BaseCore.js:659`

Initializes the class hierarchy for the instance, which includes initializing attributes for each class defined in the class's static ATTRS property and invoking the initializer method on the prototype of each class in the hierarchy.

#### Parameters:

- `userVals` Object

  Object with configuration property name/value pairs

### `_initHierarchyData`

() private

Defined in `base/js/BaseCore.js:457`

A helper method used by _getClasses and _getAttrCfgs, which determines both the array of classes and aggregate set of attribute configurations across the class hierarchy for the instance.

### `_isLazyAttr`

(

- `name`

)
Boolean private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:369`

Checks whether or not the attribute is one which has been added lazily and still requires initialization.

#### Parameters:

- `name` String

  The name of the attribute

#### Returns:

Boolean: true if it's a lazily added attribute, false otherwise.

### `_normAttrVals`

(

- `valueHash`

)
Object private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:897`

Utility method to normalize attribute values. The base implementation simply merges the hash to protect the original.

#### Parameters:

- `valueHash` Object

  An object with attribute name/value pairs

#### Returns:

Object: An object literal with 2 properties - "simple" and "complex", containing simple and complex attribute values respectively keyed by the top level attribute name, or null, if valueHash is falsey.

### `_protectAttrs`

(

- `attrs`

)
Object deprecated protected

Inherited from AttributeCore: `attribute/js/AttributeCore.js:883`

Deprecated: Use `AttributeCore.protectAttrs()` or `Attribute.protectAttrs()` which are the same static utility method.

Utility method to protect an attribute configuration hash, by merging the entire object and the individual attr config objects.

#### Parameters:

- `attrs` Object

  A hash of attribute to configuration object pairs.

#### Returns:

Object: A protected version of the attrs argument.

### `_set`

(

- `name`
- `val`
- `[opts]`

)
Object protected chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:427`

Allows setting of readOnly/writeOnce attributes. See set for argument details.

#### Parameters:

- `name` String

  The name of the attribute.

- `val` Any

  The value to set the attribute to.

- `[opts]` Object optional

  Optional data providing the circumstances for the change.

#### Returns:

Object: A reference to the host object.

### `_setAttr`

(

- `name`
- `value`
- `[opts]`
- `force`

)
Object protected chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:443`

Provides the common implementation for the public set and protected _set methods.

See set for argument details.

#### Parameters:

- `name` String

  The name of the attribute.

- `value` Any

  The value to set the attribute to.

- `[opts]` Object optional

  Optional data providing the circumstances for the change.

- `force` Boolean

  If true, allows the caller to set values for readOnly or writeOnce attributes which have already been set.

#### Returns:

Object: A reference to the host object.

### `_setAttrs`

(

- `attrs`
- `[opts]`

)
Object protected chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:742`

Implementation behind the public setAttrs method, to set multiple attribute values.

#### Parameters:

- `attrs` Object

  An object with attributes name/value pairs.

- `[opts]` Object optional

  Optional data providing the circumstances for the change

#### Returns:

Object: A reference to the host object.

### `_setAttrVal`

(

- `attrName`
- `subAttrName`
- `prevVal`
- `newVal`
- `[opts]`
- `[attrCfg]`

)
Booolean private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:640`

Updates the stored value of the attribute in the privately held State object, if validation and setter passes.

#### Parameters:

- `attrName` String

  The attribute name.

- `subAttrName` String

  The sub-attribute name, if setting a sub-attribute property ("x.y.z").

- `prevVal` Any

  The currently stored value of the attribute.

- `newVal` Any

  The value which is going to be stored.

- `[opts]` Object optional

  Optional data providing the circumstances for the change.

- `[attrCfg]` Object optional

  Optional config hash for the attribute. This is added for performance along the critical path, where the calling method has already obtained the config from state.

#### Returns:

Booolean: true if the new attribute value was stored, false if not.

### `_setStateVal`

(

- `name`
- `value`

)
private

Inherited from AttributeCore: `attribute/js/AttributeCore.js:622`

Sets the stored value for the attribute, in either the internal state object, or the state proxy if it exits

#### Parameters:

- `name` String

  The name of the attribute

- `value` Any

  The value of the attribute

### `addAttr`

(

- `name`
- `config`
- `lazy`

)
Object chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:157`

Adds an attribute with the provided configuration to the host object.

The config argument object supports the following properties:

value <Any>
  The initial value to set on the attribute
valueFn <Function | String>

  A function, which will return the initial value to set on the attribute. This is useful for cases where the attribute configuration is defined statically, but needs to reference the host instance ("this") to obtain an initial value. If both the value and valueFn properties are defined, the value returned by the valueFn has precedence over the value property, unless it returns undefined, in which case the value property is used.

  valueFn can also be set to a string, representing the name of the instance method to be used to retrieve the value.

readOnly <boolean>
  Whether or not the attribute is read only. Attributes having readOnly set to true cannot be modified by invoking the set method.
writeOnce <boolean> or <string>
  Whether or not the attribute is "write once". Attributes having writeOnce set to true, can only have their values set once, be it through the default configuration, constructor configuration arguments, or by invoking set.

  The writeOnce attribute can also be set to the string "initOnly", in which case the attribute can only be set during initialization (when used with Base, this means it can only be set during construction)

setter <Function | String>

  The setter function used to massage or normalize the value passed to the set method for the attribute. The value returned by the setter will be the final stored value. Returning Attribute.INVALID_VALUE, from the setter will prevent the value from being stored.

  setter can also be set to a string, representing the name of the instance method to be used as the setter function.

getter <Function | String>

  The getter function used to massage or normalize the value returned by the get method for the attribute. The value returned by the getter function is the value which will be returned to the user when they invoke get.

  getter can also be set to a string, representing the name of the instance method to be used as the getter function.

validator <Function | String>

  The validator function invoked prior to setting the stored value. Returning false from the validator function will prevent the value from being stored.

  validator can also be set to a string, representing the name of the instance method to be used as the validator function.

lazyAdd <boolean>
  Whether or not to delay initialization of the attribute until the first call to get/set it. This flag can be used to over-ride lazy initialization on a per attribute basis, when adding multiple attributes through the addAttrs method.

The setter, getter and validator are invoked with the value and name passed in as the first and second arguments, and with the context ("this") set to the host object.

Configuration properties outside of the list mentioned above are considered private properties used internally by attribute, and are not intended for public use.

#### Parameters:

- `name` String

  The name of the attribute.

- `config` Object

  An object with attribute configuration property/value pairs, specifying the configuration for the attribute.

  NOTE: The configuration object is modified when adding an attribute, so if you need to protect the original values, you will need to merge the object.

- `lazy` Boolean

  (optional) Whether or not to add this attribute lazily (on the first call to get/set).

#### Returns:

Object: A reference to the host object.

### `addAttrs`

(

- `cfgs`
- `values`
- `lazy`

)
Object chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:805`

Configures a group of attributes, and sets initial values.

NOTE: This method does not isolate the configuration object by merging/cloning. The caller is responsible for merging/cloning the configuration object if required.

#### Parameters:

- `cfgs` Object

  An object with attribute name/configuration pairs.

- `values` Object

  An object with attribute name/value pairs, defining the initial values to apply. Values defined in the cfgs argument will be over-written by values in this argument unless defined as read only.

- `lazy` Boolean

  Whether or not to delay the intialization of these attributes until the first call to get/set. Individual attributes can over-ride this behavior by defining a lazyAdd configuration property in their configuration. See addAttr.

#### Returns:

Object: A reference to the host object.

### `attrAdded`

(

- `name`

)
Boolean

Inherited from AttributeCore: `attribute/js/AttributeCore.js:341`

Checks if the given attribute has been added to the host

#### Parameters:

- `name` String

  The name of the attribute to check.

#### Returns:

Boolean: true if an attribute with the given name has been added, false if it hasn't. This method will return true for lazily added attributes.

### `destroy`

() BaseCore chainable

Defined in `base/js/BaseCore.js:297`

Destroy lifecycle method. Invokes destructors for the class hierarchy.

#### Returns:

BaseCore: A reference to this object

### `get`

(

- `name`

)
Any

Inherited from AttributeCore: `attribute/js/AttributeCore.js:353`

Returns the current value of the attribute. If the attribute has been configured with a 'getter' function, this method will delegate to the 'getter' to obtain the value of the attribute.

#### Parameters:

- `name` String

  The name of the attribute. If the value of the attribute is an Object, dot notation can be used to obtain the value of a property of the object (e.g. `get("x.y.z")`)

#### Returns:

Any: The value of the attribute

### `getAttrs`

(

- `attrs`

)
Object

Inherited from AttributeCore: `attribute/js/AttributeCore.js:762`

Gets multiple attribute values.

#### Parameters:

- `attrs` Array | boolean

  Optional. An array of attribute names. If omitted, all attribute values are returned. If set to true, all attributes modified from their initial values are returned.

#### Returns:

Object: An object with attribute name/value pairs.

### `init`

(

- `cfg`

)
BaseCore chainable

Defined in `base/js/BaseCore.js:264`

Init lifecycle method, invoked during construction. Sets up attributes and invokes initializers for the class hierarchy.

#### Parameters:

- `cfg` Object

  Object with configuration property name/value pairs

#### Returns:

BaseCore: A reference to this object

### `modifyAttrs`

(

- `[ctor]`
- `configs`

)
static

Defined in `base/js/BaseCore.js:172`

Available since 3.10.0

Provides a way to safely modify a `Y.BaseCore` subclass' static `ATTRS` after the class has been defined or created.

BaseCore-based classes cache information about the class hierarchy in order to efficiently create instances. This cache includes includes the aggregated `ATTRS` configs. If the static `ATTRS` configs need to be modified after the class has been defined or create, then use this method which will make sure to clear any cached data before making any modifications.

#### Parameters:

- `[ctor]` Function optional

  The constructor function whose `ATTRS` should be modified. If a `ctor` function is not specified, then `this` is assumed to be the constructor which hosts the `ATTRS`.

- `configs` Object

  The collection of `ATTRS` configs to mix with the existing attribute configurations.

### `set`

(

- `name`
- `value`
- `[opts]`

)
Object chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:410`

Sets the value of an attribute.

#### Parameters:

- `name` String

  The name of the attribute. If the current value of the attribute is an Object, dot notation can be used to set the value of a property within the object (e.g. `set("x.y.z", 5)`).

- `value` Any

  The value to set the attribute to.

- `[opts]` Object optional

  Optional data providing the circumstances for the change.

#### Returns:

Object: A reference to the host object.

### `setAttrs`

(

- `attrs`
- `[opts]`

)
Object chainable

Inherited from AttributeCore: `attribute/js/AttributeCore.js:729`

Sets multiple attribute values.

#### Parameters:

- `attrs` Object

  An object with attributes name/value pairs.

- `[opts]` Object optional

  Optional data providing the circumstances for the change.

#### Returns:

Object: A reference to the host object.

### `toString`

() String

Defined in `base/js/BaseCore.js:754`

Default toString implementation. Provides the constructor NAME and the instance guid, if set.

#### Returns:

String: String representation for this object

## Properties

### `_allowAdHocAttrs`

Boolean protected

Defined in `base/js/BaseCore.js:100`

This property controls whether or not instances of this class should allow users to add ad-hoc attributes through the constructor configuration hash.

AdHoc attributes are attributes which are not defined by the class, and are not handled by the MyClass.NONATTRS_CFG

Default: undefined (false)

### `_ATTR_CFG`

Array private static

Defined in `base/js/BaseCore.js:74`

The list of properties which can be configured for each attribute (e.g. setter, getter, writeOnce, readOnly etc.)

### `_NON_ATTRS_CFG`

Array private static

Defined in `base/js/BaseCore.js:85`

The array of non-attribute configuration properties supported by this class.

For example `BaseCore` defines a "plugins" configuration property which should not be set up as an attribute. This property is primarily required so that when `_allowAdHocAttrs` is enabled by a class, non-attribute configuration properties don't get added as ad-hoc attributes.

### `ATTRS`

Object static

Defined in `base/js/BaseCore.js:127`

The default set of attributes which will be available for instances of this class, and their configuration. In addition to the configuration properties listed by AttributeCore's addAttr method, the attribute can also be configured with a "cloneDefaultValue" property, which defines how the statically defined value field should be protected ("shallow", "deep" and false are supported values).

By default if the value is an object literal or an array it will be "shallow" cloned, to protect the default value.

### `NAME`

String static

Defined in `base/js/BaseCore.js:114`

The string to be used to identify instances of this class.

Classes extending BaseCore, should define their own static NAME property, which should be camelCase by convention (e.g. MyClass.NAME = "myClass";).

### `name`

String deprecated

Defined in `base/js/BaseCore.js:242`

Deprecated: Use this.constructor.NAME

The string used to identify the class of this object.

## Attributes

### `destroyed`

Boolean readonly

Defined in `base/js/BaseCore.js:157`

Flag indicating whether or not this object has been through the destroy lifecycle phase.

Default: false

#### Fires event `destroyedChange`

Fires when the value for the configuration attribute `destroyed` is changed. You can listen for the event using the `on` method if you wish to be notified before the attribute's value has changed, or using the `after` method if you wish to be notified after the attribute's value has changed.

#### Parameters:

- `e` EventFacade
  An Event Facade object with the following attribute-specific properties added:
  - `prevVal` Any
    The value of the attribute, prior to it being set.
  - `newVal` Any
    The value the attribute is to be set to.
  - `attrName` String
    The name of the attribute being set.
  - `subAttrName` String
    If setting a property within the attribute's value, the name of the sub-attribute property being set.

### `initialized`

Boolean readonly

Defined in `base/js/BaseCore.js:143`

Flag indicating whether or not this object has been through the init lifecycle phase.

Default: false

#### Fires event `initializedChange`

Fires when the value for the configuration attribute `initialized` is changed. You can listen for the event using the `on` method if you wish to be notified before the attribute's value has changed, or using the `after` method if you wish to be notified after the attribute's value has changed.

#### Parameters:

- `e` EventFacade
  An Event Facade object with the following attribute-specific properties added:
  - `prevVal` Any
    The value of the attribute, prior to it being set.
  - `newVal` Any
    The value the attribute is to be set to.
  - `attrName` String
    The name of the attribute being set.
  - `subAttrName` String
    If setting a property within the attribute's value, the name of the sub-attribute property being set.