A 
    
Property whose value is lazily evaluated by a callback function.
| Name | Type | Description | 
|---|---|---|
| callback | CallbackProperty.Callback | The function to be called when the property is evaluated. | 
| isConstant | Boolean | truewhen the callback function returns the same value every time,falseif the value will change. | 
Members
readonly definitionChanged : Event
    Gets the event that is raised whenever the definition of this property changes.
The definition is changed whenever setCallback is called.
    Gets a value indicating if this property is constant.
Methods
    Compares this property to the provided property and returns
    
true if they are equal, false otherwise.
| Name | Type | Description | 
|---|---|---|
| other | Property | optional The other property. | 
Returns:
true if left and right are equal, false otherwise.
    Gets the value of the property.
    
| Name | Type | Description | 
|---|---|---|
| time | JulianDate | The time for which to retrieve the value. | 
| result | Object | optional The object to store the value into, if omitted, a new instance is created and returned. | 
Returns:
    The modified result parameter or a new instance if the result parameter was not supplied or is unsupported.
    
    Sets the callback to be used.
    
| Name | Type | Description | 
|---|---|---|
| callback | CallbackProperty.Callback | The function to be called when the property is evaluated. | 
| isConstant | Boolean | truewhen the callback function returns the same value every time,falseif the value will change. | 
Type Definitions
    A function that returns the value of the property.
    
| Name | Type | Description | 
|---|---|---|
| time | JulianDate | The time for which to retrieve the value. | 
| result | Object | optional The object to store the value into. If omitted, the function must create and return a new instance. | 
Returns:
    The modified result parameter, or a new instance if the result parameter was not supplied or is unsupported.
    
