groovy.lang
Interface MetaClass

groovy.lang.MetaObjectProtocol
  groovy.lang.MetaClass

All Superinterfaces:

MetaObjectProtocol

interface MetaClass
extends MetaObjectProtocol

A MetaClass within Groovy defines the behaviour of any given Groovy or Java class. The MetaClass interface defines two parts. The client API, which is defined via the extend MetaObjectProtocol interface and the contract with the Groovy runtime system. In general the compiler and Groovy runtime engine interact with methods on this class whilst MetaClass clients interact with the method defined by the MetaObjectProtocol interface

see:

MetaClassImpl

see:

MetaObjectProtocol

author:

John Wilson

author:

Graeme Rocher

getAttribute

public Object getAttribute(Class sender, Object receiver, String messageName, boolean useSuper)

Retrieves the value of an attribute (field). This method is to support the Groovy runtime and not for general client API usage.

param:

sender The class of the object that requested the attribute

param:

receiver The instance

param:

messageName The name of the attribute

param:

useSuper Whether to look-up on the super class or not

return:

The attribute value

getClassNode

public ClassNode getClassNode()

Obtains a reference to the original AST for the MetaClass if it is available at runtime

return:

The original AST or null if it cannot be returned

getMetaMethods

public List getMetaMethods()

Retrieves a list of MetaMethods held by this class

return:

A list of MetaMethods

getMethods

public List getMethods()

Retrieves a list of MetaMethods held by the class

return:

A list of MetaMethods

getProperties

public List getProperties()

Retrives a list of MetaProperty instances that the MetaClass has

see:

MetaProperty

return:

A list of MetaProperty instances

getProperty

public Object getProperty(Class sender, Object receiver, String property, boolean isCallToSuper, boolean fromInsideClass)

Retrieves a property on the given receiver for the specified arguments. The sender is the class that is requesting the property from the object. The MetaClass will attempt to establish the method to invoke based on the name and arguments provided.

The isCallToSuper and fromInsideClass help the Groovy runtime perform optimisations on the call to go directly to the super class if necessary

param:

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

param:

receiver The Object which the property is being retrieved from

param:

property The name of the property

param:

isCallToSuper Whether the call is to a super class property

param:

fromInsideClass ??

return:

The properties value

initialize

public void initialize()

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.

invokeMethod

public Object invokeMethod(Class sender, Object receiver, String methodName, Object[] arguments, boolean isCallToSuper, boolean fromInsideClass)

Invokes a method on the given receiver for the specified arguments. The sender is the class that invoked the method on the object. The MetaClass will attempt to establish the method to invoke based on the name and arguments provided.

The isCallToSuper and fromInsideClass help the Groovy runtime perform optimisations on the call to go directly to the super class if necessary

param:

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

param:

receiver The object which the method was invoked on

param:

methodName The name of the method

param:

arguments The arguments to the method

param:

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

param:

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

return:

The return value of the method

invokeMissingMethod

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

Attempts to invoke the methodMissing method otherwise throws a MissingMethodException

see:

MissingMethodException

param:

instance The instance to invoke methodMissing on

param:

methodName The name of the method

param:

arguments The arguments to the method

return:

The results of methodMissing or throws MissingMethodException

invokeMissingProperty

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

Invokes the propertyMissing method otherwise throws a MissingPropertyException

param:

instance The instance of the class

param:

propertyName The name of the property

param:

optionalValue The value of the property which could be null in the case of a getter

param:

isGetter Whether the missing property event was the result of a getter or a setter

return:

The result of the propertyMissing method or throws MissingPropertyException

pickMethod

public MetaMethod pickMethod(String methodName, Class[] arguments)

Selects a method by name and argument classes. This method does not search for an exact match, it searches for a compatible method. For this the method selection mechanism is used as provided by the implementation of this MetaClass. pickMethod may or may not be used during the method selection process when invoking a method. There is no warranty for that.

return:

a matching MetaMethod or null

throws:

GroovyRuntimeException if there is more than one matching method

param:

methodName the name of the method to pick

param:

arguments the method arguments

selectConstructorAndTransformArguments

public int selectConstructorAndTransformArguments(int numberOfConstructors, Object[] arguments)

Internal method to support Groovy runtime. Not for client usage.

param:

numberOfConstructors The number of constructors

param:

arguments The arguments

return:

selected index

setAttribute

public void setAttribute(Class sender, Object receiver, String messageName, Object messageValue, boolean useSuper, boolean fromInsideClass)

Sets the value of an attribute (field). This method is to support the Groovy runtime and not for general client API usage.

param:

sender The class of the object that requested the attribute

param:

receiver The instance

param:

messageName The name of the attribute

param:

messageValue The value of the attribute

param:

useSuper Whether to look-up on the super class or not

param:

fromInsideClass Whether the call happened from the inside or the outside of a class

setProperty

public void setProperty(Class sender, Object receiver, String property, Object value, boolean isCallToSuper, boolean fromInsideClass)

Retrieves a property on the given receiver for the specified arguments. The sender is the class that is requesting the property from the object. The MetaClass will attempt to establish the method to invoke based on the name and arguments provided.

The isCallToSuper and fromInsideClass help the Groovy runtime perform optimisations on the call to go directly to the super class if necessary

param:

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

param:

receiver The Object which the property is being set on

param:

property The name of the property

param:

value The new value of the property to set

param:

isCallToSuper Whether the call is to a super class property

param:

fromInsideClass ??

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