Hi,
I thought that SWT enthusiasts might be interested in a problem that I =
am having when trying to build a "simple" JFace/SWT application scripted =
using Jython. (See below if SWT and JFace are new to you.) Any =
suggestions or help in interpreting the error messages would be =
gratefully received.
Thanks,
Ian

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Contents
  a.. Discussion
  b.. ApplicationJFaceSWT.java in Java
  c.. ApplicationJFaceSWT.py in Jython
  d.. Error messages
  e.. SWT/JFace
  f.. Modifying jython.bat to put swt and jface .jar files in the =
classpath
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Discussion
I have been trying to translate a SWT JFace application into Jython. =
This might not be what Jython is for or is good at? (I am new to all of =
Jython, Java, Eclipse and the SWT/JFace libraries.) The Java example =
works but the Jython does not. For the Jython example, the application =
window opens, but when a menu item is selected the application crashes. =
The Jython code generates the GUI without difficulty - it is the action =
event handling that fails to work.

I am using Jython 2.1, the latest Sun runtime j2re1.4.1_04, on a PC =
platform with Windows 2000.=20
(I edit Jy/CPython in Eclipse, using the pyeclipse plug in.)

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ApplicationJFaceSWT.java in Java

/*
 * A simple application using JFace
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/window/Window.html
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/window/ApplicationWindow.html
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/action/Action.html
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/action/MenuManager.html
 * http://www-106.ibm.com/developerworks/java/library/os-ecgui1/
 *=20
 * Must have boot, jface, runtime, swt and workbench .jar files on build =
path
 * Part of the Eclipse distribution http://www.eclipse.org
 */

import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.GroupMarker;
import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.window.ApplicationWindow;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;

public class ApplicationJFaceSWT extends ApplicationWindow {

	public ApplicationJFaceSWT(Shell parentShell) {
		super(parentShell);
	}

	public static void main(String[] args) {
		Display display =3D new Display(); //swt.widgets
		Shell shell =3D new Shell(display); //swt.widgets
		ApplicationJFaceSWT application =3D new ApplicationJFaceSWT(shell);
		application.createComponents();
		application.open(); //jface.window.Window
		display.close();
	}

	//-----------------------------------------------
	// All application specific methods=20
	// (i.e. those not overriding superclass methods)
	//-----------------------------------------------
	public void createComponents() {
		// --- call ApplicationWindow methods
		addMenuBar();
		//addStatusLine();
		//addToolBar(SWT.FLAT | SWT.WRAP);
		// --- call Window method
		setBlockOnOpen(true);
	};

	private MenuManager createMyMenu1Menu() {
		MenuManager menu =3D new MenuManager("MyMenu1", "M01MI01");
		menu.add(new GroupMarker("MyMenu1Item1"));
		menu.add(createMyMenu1Item1Action());
		return menu;
	}

	private Action createMyMenu1Item1Action() {
		return new Action() { // Anonymous inner class
			public String getText() {
				return "Text for Menu 1 Item 1";
			}

			public void run() {
				System.out.println("Implement menu item 1.1 consequence");
			}
		};
	}

	//-----------------------------------------------
	//	Methods that override superclass methods
	//-----------------------------------------------
	protected MenuManager createMenuManager() {
		MenuManager menuManager =3D new MenuManager();
		menuManager.add(createMyMenu1Menu());
		return menuManager;
	}

	protected void handleShellCloseEvent() {
		System.out.println("Thank you. Goodbye.");
		setReturnCode(CANCEL);
		close();
	}

	// createContents - extend or reimplement to create controls before =
window opens=20
	protected Control createContents(Composite parent) {
		Table composite =3D new Table(parent, SWT.BORDER);
		return composite;
	}

}


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ApplicationJFaceSWT.py in Jython

"""/
 * A simple application using JFace
 * See
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/window/Window.html
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/window/ApplicationWindow.html
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/action/Action.html
 * =
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/action/MenuManager.html
 * http://www-106.ibm.com/developerworks/java/library/os-ecgui1/
 *=20
 * Must have boot, jface, runtime, swt and workbench .jar files on =
Jython classpath
 * Part of the Eclipse distribution http://www.eclipse.org
"""
import java
import org.eclipse.jface
import org.eclipse.swt
#import org.eclipse.core
#import org.eclipse.ui

#  This named class is in lieu of an anonymous inner class in Java
class MyMenu1Item1Action(org.eclipse.jface.action.Action):
    def getText(self):
        print("In getText")
        return "Menu 1 Item 1"
    def run(self):
        print("In run")
        pass
               =20
class ApplicationJFaceSWT(org.eclipse.jface.window.ApplicationWindow):
    #---------------------------------------------------
    #  Novel methods (not overridden superclass methods)
    #---------------------------------------------------
    def createComponents(self):
        print("Creating components: menubar")
        self.addMenuBar()
        #addStatusLine();
        #addToolBar(org.eclipse.swt.SWT.FLAT | =
org.eclipse.swt.SWT.WRAP);
        self.setBlockOnOpen(1)
       =20
    def createMyMenu1Menu(self):
        print("Creating MyMenu1 menu")
        menumgr =3D org.eclipse.jface.action.MenuManager("MyMenu1", =
"M01MI01")
        menumgr.add(org.eclipse.jface.action.GroupMarker("Menu1Item1"))
        menumgr.add(self.createMyMenu1Item1Action())
        return menumgr

    def createMyMenu1Item1Action(self):
        print("Creating MyMenu1Item1 action")
        return MyMenu1Item1Action()=20
   =20
    #---------------------------------------------------
    #  Overridden superclass methods
    #---------------------------------------------------
    def createMenuManager(self):
        print("Creating menu manager")
        menuManager =3D org.eclipse.jface.action.MenuManager()
        menuManager.add(self.createMyMenu1Menu())=20
        return menuManager
   =20
    def handleShellCloseEvent(self):
        print("Goodbye!")
        self.setReturnCode(self.CANCEL)
        self.close()

    def createContents(self, parentComposite):
        print("Creating contents")
        childComposite =3D =
org.eclipse.swt.widgets.Table(parentComposite, =
org.eclipse.swt.SWT.BORDER)
        return childComposite

if __name__ =3D=3D '__main__':
    print("Starting __main__")
    display =3D org.eclipse.swt.widgets.Display()  =20
    shell =3D org.eclipse.swt.widgets.Shell(display)
    application =3D ApplicationJFaceSWT(shell)=20
    application.createComponents()
    application.open()      =20

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Error messages

java.lang.NoClassDefFoundError: =
org/eclipse/core/internal/boot/DelegatingURLClassLoader
at org.eclipse.core.runtime.Platform.getDebugOption(Platform.java:272)
at =
org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(Act=
ionContributionItem.java:452)
at =
org.eclipse.jface.action.ActionContributionItem.handleWidgetEvent(ActionC=
ontributionItem.java:403)
at =
org.eclipse.jface.action.ActionContributionItem.access$0(ActionContributi=
onItem.java:397)
at =
org.eclipse.jface.action.ActionContributionItem$ActionListener.handleEven=
t(ActionContributionItem.java:72)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:81)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:840)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:1838)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:1545)
at org.eclipse.jface.window.Window.runEventLoop(Window.java:583)
at org.eclipse.jface.window.Window.open(Window.java:563)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at =
org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java)
at org.python.core.PyMethod.__call__(PyMethod.java)
at org.python.core.PyObject.__call__(PyObject.java)
at org.python.core.PyInstance.invoke(PyInstance.java)
at org.python.pycode._pyx0.f$0(ApplicationJFaceSWT.py:75)
at org.python.pycode._pyx0.call_function(ApplicationJFaceSWT.py)
at org.python.core.PyTableCode.call(PyTableCode.java)
at org.python.core.PyCode.call(PyCode.java)
at org.python.core.Py.runCode(Py.java)
at org.python.core.__builtin__.execfile_flags(__builtin__.java)
at org.python.util.PythonInterpreter.execfile(PythonInterpreter.java)
at org.python.util.jython.main(jython.java)

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SWT/JFace
The standard widget toolkit (SWT), developed by IBM and now open source =
is an alternative GUI framework to Sun's AWT/Swing and is used to build =
the Eclipse Java IDE and development framework. Both Swing and SWT have =
their advantages and disadvantages; and these are discussed at length on =
other newsgroups. SWT is useful for people who wish to write plug-ins =
for the Eclipse framework. On top of SWT lives JFace. From an IBM =
developworks article=20
http://www-106.ibm.com/developerworks/java/library/os-ecgui1/=20
I quote:

"Two of its major components are a graphical library called SWT and a =
matching utility framework called JFace. I'll concentrate on these =
components in this article. The Eclipse Technical Overview on the =
Eclipse Web site (see Resources later in this article) describes them =
like this:
  a.. SWT is a widget set and graphics library integrated with the =
native window system but with an OS-independent API.=20
  b.. JFace is a UI toolkit implemented using SWT that simplifies common =
UI programming tasks. JFace is window-system-independent in both its API =
and implementation, and is designed to work with SWT without hiding it."

The Java docs are here:
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/index.html

See also:
http://www.eclipse.org/
http://www.eclipse.org/swt/
http://www-106.ibm.com/developerworks/java/library/os-ecgui1/
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/window/Window.html
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/window/ApplicationWindow.html
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/action/Action.html
http://www.eclipse.org/documentation/html/plugins/org.eclipse.platform.do=
c.isv/doc/reference/api/org/eclipse/jface/action/MenuManager.html
=20
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Modifying jython.bat

So that jython can work with SWT JFace, I have modified my jython.bat =
file as follows. There may be a better way. Suggestions?

set PATH_SWT=3D D:\Program =
Files\eclipse\plugins\org.eclipse.core.boot_2.1.1\boot.jar
set PATH_SWT=3D%PATH_SWT%;D:\Program =
Files\eclipse\plugins\org.eclipse.jface_2.1.1\jface.jar
set PATH_SWT=3D%PATH_SWT%;D:\Program =
Files\eclipse\plugins\org.eclipse.core.runtime_2.1.1\runtime.jar
set PATH_SWT=3D%PATH_SWT%;D:\Program =
Files\eclipse\plugins\org.eclipse.swt.win32_2.1.1\ws\win32\swt.jar
set PATH_SWT=3D%PATH_SWT%;D:\Program =
Files\eclipse\plugins\org.eclipse.ui.workbench_2.1.1\workbench.jar

"D:\Program Files\Java\j2re1.4.1_04\bin\java.exe" =
"-Dpython.home=3DD:\Program Files\Jython21" -classpath "D:\Program =
Files\Jython21\jython.jar;%CLASSPATH%;%PATH_SWT%" org.python.util.jython =
%ARGS%