Package org.mozilla.javascript

Interface ConstProperties

All Known Implementing Classes:

BaseFunction, BoundFunction, Environment, FunctionObject, Global, IdFunctionObject, IdScriptableObject, ImporterTopLevel, LiveComponent, LiveObject, ModuleScope, NativeArray, NativeArrayBuffer, NativeArrayBufferView, NativeCall, NativeCallSite, NativeContinuation, NativeDataView, NativeFloat32Array, NativeFloat64Array, NativeFunction, NativeGenerator, NativeInt16Array, NativeInt32Array, NativeInt8Array, NativeIterator, NativeJavaConstructor, NativeJavaMethod, NativeJavaPackage, NativeJavaTopPackage, NativeJSON, NativeObject, NativeRegExp, NativeTypedArrayView, NativeUint16Array, NativeUint32Array, NativeUint8Array, NativeUint8ClampedArray, Require, ScriptableObject, TopLevel, XMLObject

public interface ConstProperties

Method Summary

Modifier and Type	Method	Description
void	defineConst(java.lang.String name, Scriptable start)	Reserves a definition spot for a const.
boolean	isConst(java.lang.String name)	Returns true if the named property is defined as a const on this object.
void	putConst(java.lang.String name, Scriptable start, java.lang.Object value)	Sets a named const property in this object.

Method Detail

putConst

void putConst(java.lang.String name,
              Scriptable start,
              java.lang.Object value)

Sets a named const property in this object.

The property is specified by a string name as defined for Scriptable.get.

The possible values that may be passed in are as defined for Scriptable.get. A class that implements this method may choose to ignore calls to set certain properties, in which case those properties are effectively read-only.

For properties defined in a prototype chain, use putProperty in ScriptableObject.

Note that if a property a is defined in the prototype p of an object o, then evaluating o.a = 23 will cause set to be called on the prototype p with o as the start parameter. To preserve JavaScript semantics, it is the Scriptable object's responsibility to modify o.

This design allows properties to be defined in prototypes and implemented in terms of getters and setters of Java values without consuming slots in each instance.

The values that may be set are limited to the following:

• java.lang.Boolean objects
• java.lang.String objects
• java.lang.Number objects
• org.mozilla.javascript.Scriptable objects
• null
• The value returned by Context.getUndefinedValue()

Arbitrary Java objects may be wrapped in a Scriptable by first calling Context.toObject. This allows the property of a JavaScript object to contain an arbitrary Java object as a value.

Note that has will be called by the runtime first before set is called to determine in which object the property is defined. Note that this method is not expected to traverse the prototype chain, which is different from the ECMA [[Put]] operation.

Parameters:

name - the name of the property

start - the object whose property is being set

value - value to set the property to

See Also:

Scriptable.has(String, Scriptable), Scriptable.get(String, Scriptable), ScriptableObject.putProperty(Scriptable, String, Object), Context.toObject(Object, Scriptable)

defineConst

void defineConst(java.lang.String name,
                 Scriptable start)

Reserves a definition spot for a const. This will set up a definition of the const property, but set its value to undefined. The semantics of the start parameter is the same as for putConst.

Parameters:

name - The name of the property.

start - The object whose property is being reserved.

isConst

boolean isConst(java.lang.String name)

Returns true if the named property is defined as a const on this object.

Parameters:

name -

Returns:

true if the named property is defined as a const, false otherwise.