groovy.lang

Class ExpandoMetaClass

java.lang.Object

groovy.lang.MetaClassImpl

groovy.lang.ExpandoMetaClass

All Implemented Interfaces:

GroovyObject, MetaClass, MetaObjectProtocol, MutableMetaClass

public class ExpandoMetaClass
extends MetaClassImpl
implements GroovyObject

A MetaClass that implements GroovyObject and behaves like an Expando, allowing the addition of new methods on the fly

 // defines or replaces instance method:
 metaClass.myMethod = { args -> }

 // defines a new instance method
 metaClass.myMethod << { args -> }

 // creates multiple overloaded methods of the same name
 metaClass.myMethod << { String s -> } << { Integer i -> }

 // defines or replaces a static method with the 'static' qualifier
 metaClass.'static'.myMethod = { args ->  }

 // defines a new static method with the 'static' qualifier
 metaClass.'static'.myMethod << { args ->  }

 // defines a new constructor
 metaClass.constructor << { String arg -> }

 // defines or replaces a constructor
 metaClass.constructor = { String arg -> }

 // defines a new property with an initial value of "blah"
 metaClass.myProperty = "blah"

 

By default methods are only allowed to be added before initialize() is called. In other words you create a new ExpandoMetaClass, add some methods and then call initialize(). If you attempt to add new methods after initialize() has been called an error will be thrown. This is to ensure that the MetaClass can operate appropriately in multi threaded environments as it forces you to do all method additions at the beginning, before using the MetaClass. If you need more fine grained control of how a method is matched you can use DynamicMethodsMetaClass WARNING: This MetaClass uses a thread-bound ThreadLocal instance to store and retrieve properties. In addition properties stored use soft references so they are both bound by the life of the Thread and by the soft references. The implication here is you should NEVER use dynamic properties if you want their values to stick around for long periods because as soon as the JVM is running low on memory or the thread dies they will be garbage collected.

Since:

1.1

Author:

Graeme Rocher

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	ExpandoMetaClass.ExpandoMetaConstructor Handles the ability to use the left shift operator to append new constructors
protected class	ExpandoMetaClass.ExpandoMetaProperty Instances of this class are returned when using the << left shift operator.

Nested classes/interfaces inherited from class groovy.lang.MetaClassImpl

MetaClassImpl.Index

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	STATIC_QUALIFIER

Fields inherited from class groovy.lang.MetaClassImpl

EMPTY_CLASS_ARRAY, isGroovyObject, isMap, LOG, METHOD_MISSING, PROPERTY_MISSING, registry, STATIC_METHOD_MISSING, STATIC_PROPERTY_MISSING, theCachedClass, theClass

Constructor Summary

Constructors

Constructor and Description
ExpandoMetaClass(java.lang.Class theClass) Constructs a new ExpandoMetaClass instance for the given class
ExpandoMetaClass(java.lang.Class theClass, boolean register) Constructs a new ExpandoMetaClass instance for the given class optionally placing the MetaClass in the MetaClassRegistry automatically
ExpandoMetaClass(java.lang.Class theClass, boolean register, boolean allowChangesAfterInit) Constructs a new ExpandoMetaClass instance for the given class optionally placing the MetaClass in the MetaClassRegistry automatically

Method Summary

Methods

Modifier and Type	Method and Description
static void	disableGlobally() Call to disable the global use of ExpandoMetaClass
static void	enableGlobally() Call to enable global use of global use of ExpandoMetaClass within the registry.
java.util.List	getExpandoMethods() Returns a list of expando MetaMethod instances added to this ExpandoMetaClass
java.util.Collection	getExpandoProperties() Returns a list of MetaBeanProperty instances added to this ExpandoMetaClass
java.lang.Class	getJavaClass()
MetaClass	getMetaClass() Returns the metaclass for a given class.
MetaProperty	getMetaProperty(java.lang.String name) Looks up an existing MetaProperty by name
java.util.List	getMethods() Overrides the behaviour of parent getMethods() method to make MetaClass aware of added Expando methods
java.util.List	getProperties() Get all the properties defined for this type
java.lang.Object	getProperty(java.lang.Class sender, java.lang.Object object, java.lang.String name, boolean useSuper, boolean fromInsideClass) Overrides default implementation just in case getProperty method has been overriden by ExpandoMetaClass
java.lang.Object	getProperty(java.lang.Object object, java.lang.String name) Overrides default implementation just in case getProperty method has been overriden by ExpandoMetaClass
java.lang.Object	getProperty(java.lang.String property) Retrieves a property value.
java.lang.String	getPropertyForSetter(java.lang.String setterName) Returns a property name equivalent for the given setter name or null if it is not a getter
protected java.util.LinkedList	getSuperClasses() Retrieves a list of super classes.
boolean	hasMetaMethod(java.lang.String name, java.lang.Class[] args) Checks whether a MetaMethod for the given name and arguments exists
boolean	hasMetaProperty(java.lang.String name) Returns true if the MetaClass has the given property
void	initialize() complete the initlialisation process.
java.lang.Object	invokeConstructor(java.lang.Object[] arguments) Invokes a constructor for the given arguments.
java.lang.Object	invokeMethod(java.lang.Class sender, java.lang.Object object, java.lang.String methodName, java.lang.Object[] originalArguments, boolean isCallToSuper, boolean fromInsideClass) Overrides default implementation just in case invokeMethod has been overriden by ExpandoMetaClass
java.lang.Object	invokeMethod(java.lang.String name, java.lang.Object args) Invokes the given method.
java.lang.Object	invokeMissingMethod(java.lang.Object instance, java.lang.String methodName, java.lang.Object[] arguments) Overrides the default missing method behaviour and adds the capability to look up a method from super class
java.lang.Object	invokeMissingProperty(java.lang.Object instance, java.lang.String propertyName, java.lang.Object optionalValue, boolean isGetter) Overrides the default missing method behaviour and adds the capability to look up a method from the super class in the case where it has been overriden
java.lang.Object	invokeStaticMethod(java.lang.Object object, java.lang.String methodName, java.lang.Object[] arguments) Overrides default implementation just in case a static invoke method has been set on ExpandoMetaClass
protected boolean	isInitialized()
boolean	isModified() Return whether the MetaClass has been modified or not
boolean	isSetter(java.lang.String name, CachedClass[] args)
protected void	performOperationOnMetaClass(groovy.lang.ExpandoMetaClass.Callable c)
void	refreshInheritedMethods(java.util.Set modifiedSuperExpandos) Called from ExpandoMetaClassCreationHandle in the registry if it exists to setup inheritance handling
protected void	registerBeanProperty(java.lang.String property, java.lang.Object newValue) Registers a new bean property
protected void	registerInstanceMethod(java.lang.String methodName, Closure callable) Registers a new instance method for the given method name and closure on this MetaClass
protected void	registerStaticMethod(java.lang.String name, Closure callable) Registers a new static method for the given method name and closure on this MetaClass
protected void	setInitialized(boolean b)
void	setMetaClass(MetaClass metaClass) Allows the MetaClass to be replaced with a derived implementation.
void	setProperty(java.lang.Class sender, java.lang.Object object, java.lang.String name, java.lang.Object newValue, boolean useSuper, boolean fromInsideClass) Overrides default implementation just in case setProperty method has been overriden by ExpandoMetaClass
void	setProperty(java.lang.String property, java.lang.Object newValue) Sets the given property to the new value.

Methods inherited from class groovy.lang.MetaClassImpl

addMetaBeanProperty, addMetaMethod, addNewInstanceMethod, addNewStaticMethod, checkInitalised, clearInvocationCaches, dropMethodCache, dropStaticMethodCache, getAttribute, getAttribute, getAttribute, getClassNode, getMetaMethod, getMetaMethods, getMethodWithCaching, getMethodWithoutCaching, getStaticMetaMethod, getTheClass, hasProperty, invokeConstructorAt, invokeMethod, invokeMethod, invokeStaticMissingProperty, isGroovyObject, pickMethod, respondsTo, respondsTo, retrieveConstructor, retrieveMethod, retrieveStaticMethod, selectConstructorAndTransformArguments, setAttribute, setAttribute, setProperties, setProperty, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

STATIC_QUALIFIER

public static final java.lang.String STATIC_QUALIFIER

See Also:

Constant Field Values

Constructor Detail

ExpandoMetaClass

public ExpandoMetaClass(java.lang.Class theClass)

Constructs a new ExpandoMetaClass instance for the given class

Parameters:

theClass - The class that the MetaClass applies to

ExpandoMetaClass

public ExpandoMetaClass(java.lang.Class theClass,
                boolean register)

Constructs a new ExpandoMetaClass instance for the given class optionally placing the MetaClass in the MetaClassRegistry automatically

Parameters:

theClass - The class that the MetaClass applies to

register - True if the MetaClass should be registered inside the MetaClassRegistry. This defaults to true and ExpandoMetaClass will effect all instances if changed

ExpandoMetaClass

public ExpandoMetaClass(java.lang.Class theClass,
                boolean register,
                boolean allowChangesAfterInit)

Constructs a new ExpandoMetaClass instance for the given class optionally placing the MetaClass in the MetaClassRegistry automatically

Parameters:

theClass - The class that the MetaClass applies to

register - True if the MetaClass should be registered inside the MetaClassRegistry. This defaults to true and ExpandoMetaClass will effect all instances if changed

allowChangesAfterInit - Should the meta class be modifiable after initialization. Default is false.

Method Detail

invokeMissingMethod

public java.lang.Object invokeMissingMethod(java.lang.Object instance,
                                   java.lang.String methodName,
                                   java.lang.Object[] arguments)

Overrides the default missing method behaviour and adds the capability to look up a method from super class

Specified by:

invokeMissingMethod in interface MetaClass

Overrides:

invokeMissingMethod in class MetaClassImpl

Parameters:

instance - The instance to invoke methodMissing on

methodName - The name of the method

arguments - The arguments to the method

Returns:

The results of methodMissing or throws MissingMethodException

See Also:

MetaClassImpl.invokeMissingMethod(Object, String, Object[])

invokeMissingProperty

public java.lang.Object invokeMissingProperty(java.lang.Object instance,
                                     java.lang.String propertyName,
                                     java.lang.Object optionalValue,
                                     boolean isGetter)

Overrides the default missing method behaviour and adds the capability to look up a method from the super class in the case where it has been overriden

Specified by:

invokeMissingProperty in interface MetaClass

Overrides:

invokeMissingProperty in class MetaClassImpl

Parameters:

instance - The instance of the object

propertyName - The property name

optionalValue - The property value in the case of a setter

isGetter - True if it is a getter

Returns:

The return value if of a getProperty call or a MissingPropertyException is thrown

isModified

public boolean isModified()

Description copied from interface: MutableMetaClass

Return whether the MetaClass has been modified or not

Specified by:

isModified in interface MutableMetaClass

Overrides:

isModified in class MetaClassImpl

Returns:

True if it has

enableGlobally

public static void enableGlobally()

Call to enable global use of global use of ExpandoMetaClass within the registry. This has the advantage that inheritance will function correctly, but has a higher memory usage on the JVM than normal Groovy

disableGlobally

public static void disableGlobally()

Call to disable the global use of ExpandoMetaClass

initialize

public void initialize()

Description copied from interface: MetaClass

complete the initlialisation process. After this method is called no methods should be added to the meta class. Invocation of methods or access to fields/proeprties is forbidden unless this method is called. This method should contain any initialisation code, taking a longer time to complete. An example is the creation of the Reflector. It is suggested to synchronize this method.

Specified by:

initialize in interface MetaClass

Overrides:

initialize in class MetaClassImpl

isInitialized

protected boolean isInitialized()

Overrides:

isInitialized in class MetaClassImpl

setInitialized

protected void setInitialized(boolean b)

invokeConstructor

public java.lang.Object invokeConstructor(java.lang.Object[] arguments)

Description copied from interface: MetaObjectProtocol

Invokes a constructor for the given arguments. The MetaClass will attempt to pick the best argument which matches the types of the objects passed within the arguments array

Specified by:

invokeConstructor in interface MetaObjectProtocol

Overrides:

invokeConstructor in class MetaClassImpl

Parameters:

arguments - The arguments to the constructor

Returns:

An instance of the java.lang.Class that this MetaObjectProtocol object applies to

getSuperClasses

protected java.util.LinkedList getSuperClasses()

Retrieves a list of super classes. Taken from MetaClassImpl. Ideally this method should be protected

Returns:

A list of super classes

getMetaClass

public MetaClass getMetaClass()

Description copied from interface: GroovyObject

Returns the metaclass for a given class.

Specified by:

getMetaClass in interface GroovyObject

Returns:

the metaClass of this instance

getProperty

public java.lang.Object getProperty(java.lang.String property)

Description copied from interface: GroovyObject

Retrieves a property value.

Specified by:

getProperty in interface GroovyObject

Parameters:

property - the name of the property of interest

Returns:

the given property

invokeMethod

public java.lang.Object invokeMethod(java.lang.String name,
                            java.lang.Object args)

Description copied from interface: GroovyObject

Invokes the given method.

Specified by:

invokeMethod in interface GroovyObject

Parameters:

name - the name of the method to call

args - the arguments to use for the method call

Returns:

the result of invoking the method

setMetaClass

public void setMetaClass(MetaClass metaClass)

Description copied from interface: GroovyObject

Allows the MetaClass to be replaced with a derived implementation.

Specified by:

setMetaClass in interface GroovyObject

Parameters:

metaClass - the new metaclass

setProperty

public void setProperty(java.lang.String property,
               java.lang.Object newValue)

Description copied from interface: GroovyObject

Sets the given property to the new value.

Specified by:

setProperty in interface GroovyObject

Parameters:

property - the name of the property of interest

newValue - the new value for the property

performOperationOnMetaClass

protected void performOperationOnMetaClass(groovy.lang.ExpandoMetaClass.Callable c)

registerBeanProperty

protected void registerBeanProperty(java.lang.String property,
                        java.lang.Object newValue)

Registers a new bean property

Parameters:

property - The property name

newValue - The properties initial value

registerInstanceMethod

protected void registerInstanceMethod(java.lang.String methodName,
                          Closure callable)

Registers a new instance method for the given method name and closure on this MetaClass

Parameters:

methodName - The method name

callable - The callable Closure

getMethods

public java.util.List getMethods()

Overrides the behaviour of parent getMethods() method to make MetaClass aware of added Expando methods

Specified by:

getMethods in interface MetaClass

Specified by:

getMethods in interface MetaObjectProtocol

Overrides:

getMethods in class MetaClassImpl

Returns:

A list of MetaMethods

See Also:

MetaObjectProtocol.getMethods()

getProperties

public java.util.List getProperties()

Description copied from class: MetaClassImpl

Get all the properties defined for this type

Specified by:

getProperties in interface MetaClass

Specified by:

getProperties in interface MetaObjectProtocol

Overrides:

getProperties in class MetaClassImpl

Returns:

a list of MetaProperty objects

See Also:

MetaProperty

registerStaticMethod

protected void registerStaticMethod(java.lang.String name,
                        Closure callable)

Registers a new static method for the given method name and closure on this MetaClass

Parameters:

name - The method name

callable - The callable Closure

getJavaClass

public java.lang.Class getJavaClass()

Returns:

The Java class enhanced by this MetaClass

refreshInheritedMethods

public void refreshInheritedMethods(java.util.Set modifiedSuperExpandos)

Called from ExpandoMetaClassCreationHandle in the registry if it exists to setup inheritance handling

Parameters:

modifiedSuperExpandos - A list of modified super ExpandoMetaClass

getExpandoMethods

public java.util.List getExpandoMethods()

Returns a list of expando MetaMethod instances added to this ExpandoMetaClass

Returns:

the expandoMethods

getExpandoProperties

public java.util.Collection getExpandoProperties()

Returns a list of MetaBeanProperty instances added to this ExpandoMetaClass

Returns:

the expandoProperties

invokeMethod

public java.lang.Object invokeMethod(java.lang.Class sender,
                            java.lang.Object object,
                            java.lang.String methodName,
                            java.lang.Object[] originalArguments,
                            boolean isCallToSuper,
                            boolean fromInsideClass)

Overrides default implementation just in case invokeMethod has been overriden by ExpandoMetaClass

Specified by:

invokeMethod in interface MetaClass

Overrides:

invokeMethod in class MetaClassImpl

Parameters:

sender - The java.lang.Class instance that invoked the method

object - The object which the method was invoked on

methodName - The name of the method

originalArguments - The arguments to the method

isCallToSuper - Whether the method is a call to a super class method

fromInsideClass - Whether the call was invoked from the inside or the outside of the class

Returns:

The return value of the method

See Also:

MetaClassImpl.invokeMethod(Class, Object, String, Object[], boolean, boolean)

invokeStaticMethod

public java.lang.Object invokeStaticMethod(java.lang.Object object,
                                  java.lang.String methodName,
                                  java.lang.Object[] arguments)

Overrides default implementation just in case a static invoke method has been set on ExpandoMetaClass

Specified by:

invokeStaticMethod in interface MetaObjectProtocol

Overrides:

invokeStaticMethod in class MetaClassImpl

Parameters:

object - An instance of the class returned by the getTheClass() method or the class itself

methodName - The name of the method

arguments - The arguments to the method

Returns:

The return value of the method which is null if the return type is void

See Also:

MetaClassImpl.invokeStaticMethod(Object, String, Object[])

getProperty

public java.lang.Object getProperty(java.lang.Class sender,
                           java.lang.Object object,
                           java.lang.String name,
                           boolean useSuper,
                           boolean fromInsideClass)

Overrides default implementation just in case getProperty method has been overriden by ExpandoMetaClass

Specified by:

getProperty in interface MetaClass

Overrides:

getProperty in class MetaClassImpl

Parameters:

sender - The java.lang.Class instance that requested the property

object - The Object which the property is being retrieved from

name - The name of the property

useSuper - Whether the call is to a super class property

fromInsideClass - ??

Returns:

the given property's value on the object

See Also:

MetaClassImpl.getProperty(Class, Object, String, boolean, boolean)

getProperty

public java.lang.Object getProperty(java.lang.Object object,
                           java.lang.String name)

Overrides default implementation just in case getProperty method has been overriden by ExpandoMetaClass

Specified by:

getProperty in interface MetaObjectProtocol

Overrides:

getProperty in class MetaClassImpl

Parameters:

object - An instance of the class returned by the getTheClass() method

name - The name of the property to retrieve the value for

Returns:

The properties value

See Also:

MetaClassImpl.getProperty(Object, String)

setProperty

public void setProperty(java.lang.Class sender,
               java.lang.Object object,
               java.lang.String name,
               java.lang.Object newValue,
               boolean useSuper,
               boolean fromInsideClass)

Overrides default implementation just in case setProperty method has been overriden by ExpandoMetaClass

Specified by:

setProperty in interface MetaClass

Overrides:

setProperty in class MetaClassImpl

Parameters:

sender - The java.lang.Class instance that is mutating the property

object - The Object which the property is being set on

name - The name of the property

newValue - The new value of the property to set

useSuper - Whether the call is to a super class property

fromInsideClass - ??

See Also:

MetaClassImpl.setProperty(Class, Object, String, Object, boolean, boolean)

getMetaProperty

public MetaProperty getMetaProperty(java.lang.String name)

Looks up an existing MetaProperty by name

Specified by:

getMetaProperty in interface MetaObjectProtocol

Overrides:

getMetaProperty in class MetaClassImpl

Parameters:

name - The name of the MetaProperty

Returns:

The MetaProperty or null if it doesn't exist

See Also:

MetaObjectProtocol.getMetaProperty(String)

hasMetaProperty

public boolean hasMetaProperty(java.lang.String name)

Returns true if the MetaClass has the given property

Parameters:

name - The name of the MetaProperty

Returns:

True it exists as a MetaProperty

hasMetaMethod

public boolean hasMetaMethod(java.lang.String name,
                    java.lang.Class[] args)

Checks whether a MetaMethod for the given name and arguments exists

Parameters:

name - The name of the MetaMethod

args - The arguments to the meta method

Returns:

True if the method exists otherwise null

getPropertyForSetter

public java.lang.String getPropertyForSetter(java.lang.String setterName)

Returns a property name equivalent for the given setter name or null if it is not a getter

Parameters:

setterName - The setter name

Returns:

The property name equivalent

isSetter

public boolean isSetter(java.lang.String name,
               CachedClass[] args)