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bsh
Class This  view This download This.java

java.lang.Object
  extended bybsh.This
All Implemented Interfaces:
java.lang.Runnable, java.io.Serializable
Direct Known Subclasses:
JThis, XThis

public class This
extends java.lang.Object
implements java.io.Serializable, java.lang.Runnable

'This' is the type of bsh scripted objects. A 'This' object is a bsh scripted object context. It holds a namespace reference and implements event listeners and various other interfaces. This holds a reference to the declaring interpreter for callbacks from outside of bsh.


Field Summary
(package private)  Interpreter declaringInterpreter
          This is the interpreter running when the This ref was created.
(package private)  NameSpace namespace
          The namespace that this This reference wraps.
 
Constructor Summary
protected This(NameSpace namespace, Interpreter declaringInterpreter)
           
 
Method Summary
static void bind(This ths, NameSpace namespace, Interpreter declaringInterpreter)
          Bind a This reference to a parent's namespace with the specified declaring interpreter.
 java.lang.Object getInterface(java.lang.Class clas)
          Get a version of this scripted object implementing the specified interface.
 java.lang.Object getInterface(java.lang.Class[] ca)
          Get a version of this scripted object implementing the specified interfaces.
 NameSpace getNameSpace()
           
(package private) static This getThis(NameSpace namespace, Interpreter declaringInterpreter)
          getThis() is a factory for bsh.This type references.
 java.lang.Object invokeMethod(java.lang.String name, java.lang.Object[] args)
          Invoke specified method as from outside java code, using the declaring interpreter and current namespace.
 java.lang.Object invokeMethod(java.lang.String methodName, java.lang.Object[] args, Interpreter interpreter, CallStack callstack, SimpleNode callerInfo)
          Invoke a method in this namespace with the specified args, interpreter reference, callstack, and caller info.
 void run()
          This method will be called by whoever wishes to run your class implementing Runnable.
 java.lang.String toString()
          Convert this Object to a human-readable String.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

namespace

NameSpace namespace
The namespace that this This reference wraps.


declaringInterpreter

transient Interpreter declaringInterpreter
This is the interpreter running when the This ref was created. It's used as a default interpreter for callback through the This where there is no current interpreter instance e.g. interface proxy or event call backs from outside of bsh.

Constructor Detail

This

protected This(NameSpace namespace,
               Interpreter declaringInterpreter)
Method Detail

getThis

static This getThis(NameSpace namespace,
                    Interpreter declaringInterpreter)
getThis() is a factory for bsh.This type references. The capabilities of ".this" references in bsh are version dependent up until jdk1.3. The version dependence was to support different default interface implementations. i.e. different sets of listener interfaces which scripted objects were capable of implementing. In jdk1.3 the reflection proxy mechanism was introduced which allowed us to implement arbitrary interfaces. This is fantastic. A This object is a thin layer over a namespace, comprising a bsh object context. We create it here only if needed for the namespace. Note: this method could be considered slow because of the way it dynamically factories objects. However I've also done tests where I hard-code the factory to return JThis and see no change in the rough test suite time. This references are also cached in NameSpace.


getInterface

public java.lang.Object getInterface(java.lang.Class clas)
                              throws UtilEvalError
Get a version of this scripted object implementing the specified interface.


getInterface

public java.lang.Object getInterface(java.lang.Class[] ca)
                              throws UtilEvalError
Get a version of this scripted object implementing the specified interfaces.


getNameSpace

public NameSpace getNameSpace()

toString

public java.lang.String toString()
Description copied from class: java.lang.Object
Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() 55 and such.

It is typical, but not required, to ensure that this method never completes abruptly with a java.lang.RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).


run

public void run()
Description copied from interface: java.lang.Runnable
This method will be called by whoever wishes to run your class implementing Runnable. Note that there are no restrictions on what you are allowed to do in the run method, except that you cannot throw a checked exception.

Specified by:
run in interface java.lang.Runnable

invokeMethod

public java.lang.Object invokeMethod(java.lang.String name,
                                     java.lang.Object[] args)
                              throws EvalError
Invoke specified method as from outside java code, using the declaring interpreter and current namespace. The call stack will indicate that the method is being invoked from outside of bsh in native java code. Note: you must still wrap/unwrap args/return values using Primitive/Primitive.unwrap() for use outside of BeanShell.


invokeMethod

public java.lang.Object invokeMethod(java.lang.String methodName,
                                     java.lang.Object[] args,
                                     Interpreter interpreter,
                                     CallStack callstack,
                                     SimpleNode callerInfo)
                              throws EvalError
Invoke a method in this namespace with the specified args, interpreter reference, callstack, and caller info.

Note: If you use this method outside of the bsh package and wish to use variables with primitive values you will have to wrap them using bsh.Primitive. Consider using This getInterface() to make a true Java interface for invoking your scripted methods.

This method also implements the default object protocol of toString(), hashCode() and equals() and the invoke() meta-method handling as a last resort.

Note: the invoke() method will not catch the object method (toString, ...). If you want to override them you have to script them directly.


bind

public static void bind(This ths,
                        NameSpace namespace,
                        Interpreter declaringInterpreter)
Bind a This reference to a parent's namespace with the specified declaring interpreter. Also re-init the callstack. It's necessary to bind a This reference before it can be used after deserialization. This is used by the bsh load() command.

This is a static utility method because it's used by a bsh command bind() and the interpreter doesn't currently allow access to direct methods of This objects (small hack)