API Docs for: 3.8.0
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AttributeCore Class

Module: attribute-core
Parent Module: attribute

AttributeCore provides the lightest level of configurable attribute support. It is designed to be augmented on to a host class, and provides the host with the ability to configure attributes to store and retrieve state, but without support for attribute change events.

For example, attributes added to the host can be configured:

  • As read only.
  • As write once.
  • With a setter function, which can be used to manipulate values passed to Attribute's set method, before they are stored.
  • With a getter function, which can be used to manipulate stored values, before they are returned by Attribute's get method.
  • With a validator function, to validate values before they are stored.

See the addAttr method, for the complete set of configuration options available for attributes.

Object/Classes based on AttributeCore can augment AttributeObservable (with true for overwrite) and AttributeExtras to add attribute event and additional, less commonly used attribute methods, such as modifyAttr, removeAttr and reset.

Methods

_addAttrs

(
  • cfgs
  • values
  • lazy
)
private

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
)
private

Finishes initializing an attribute which has been lazily added.

Parameters:

  • name Object

    The name of the attribute

_getAttr

(
  • name
)
Any protected chainable

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.

_getAttrInitVal

(
  • attr
  • cfg
  • initValues
)
Any private

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

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.

_getStateVal

(
  • name
)
Any private

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

Returns:

Any: The stored value of the attribute

_initAttrHost

(
  • attrs
  • values
  • lazy
)
private

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).

_initAttrs

(
  • attrs
  • values
  • lazy
)
protected

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).

_isLazyAttr

(
  • name
)
Boolean private

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

Utility method to split out simple attribute name/value pairs ("x") from complex attribute name/value pairs ("x.y.z"), so that complex attributes can be keyed by the top level attribute name.

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

Defined in attribute/js/AttributeCore.js:815

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
)
Object protected chainable

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.

Returns:

Object: A reference to the host object.

_setAttr

(
  • name
  • value
  • opts
  • force
)
Object protected chainable

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 event data to be mixed into the event facade passed to subscribers of the attribute's change event. This is currently a hack. There's no real need for the AttributeCore implementation to support this parameter, but breaking it out into AttributeObservable, results in additional function hops for the critical path.

  • 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
)
Object protected chainable

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

Parameters:

  • attrs Object

    An object with attributes name/value pairs.

Returns:

Object: A reference to the host object.

_setAttrVal

(
  • attrName
  • subAttrName
  • prevVal
  • newVal
)
Booolean private

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.

Returns:

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

_setStateVal

(
  • name
  • value
)
private

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

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

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

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.

get

(
  • name
)
Any

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

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.

protectAttrs

(
  • attrs
)
Object static

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
  • value
)
Object chainable

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.

Returns:

Object: A reference to the host object.

setAttrs

(
  • attrs
)
Object chainable

Sets multiple attribute values.

Parameters:

  • attrs Object

    An object with attributes name/value pairs.

Returns:

Object: A reference to the host object.

Properties

_ATTR_CFG

Array protected static

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

This property is used internally as a whitelist for faster Y.mix operations.

INVALID_VALUE

Object final static

The value to return from an attribute setter in order to prevent the set from going through.

You can return this value from your setter if you wish to combine validator and setter functionality into a single setter function, which either returns the massaged value to be stored or AttributeCore.INVALID_VALUE to prevent invalid values from being stored.