Re: Java and Objective-C

[Bill Bumgarner]

Thank you -- this is the kind of side by side, purely code oriented, set of comparisons that I think are both largely missing and generally quite useful.

Comments inline.

On Jun 7, 2008, at 1:30 PM, Denis Bohm wrote:

The Objective-C example on that page is:

- (void)setGridVisible:(NSNumber *)flag {
   BOOL flagValue = [flag boolValue];
   if (gvFlags.showGrid != flagValue) {

       gvFlags.showGrid = flagValue;
       if (flagValue)
           [graphicView resetGUP];
       [graphicView cache:[graphicView bounds]];
       [undoManager registerUndoWithTarget:self
               selector:@selector(setGridVisible:)
               object:currentValue];

NSNumber *currentValue = [NSNumber numberWithBool:gvFlags.showGrid];

I would generally write this as:





For example:

[[NSUndoManager prepareWithInvocationTarget: self] setGridVisible: currentValue]; In particular, the above form allows one to undo any random state change and not just one that can be represented by a method that takes a single argument as a parameter. [[NSUndoManager prepareWithInvocationTarget: self] setFrame: myRect animate: YES spline: splineStruct]; -setFrame:animate:spline: is a method that only exists in my application.

       [undoManager setActionName:GRID_OP];
   }

Something similar in Java could be done as:

void setGridVisible(boolean flagValue) {
        if (gvFlags.showGrid != flagValue) {
                boolean currentValue = gvFlags.showGrid;
                gvFlags.showGrid = flagValue;
                if (flagValue) {
                        graphicView.resetGUP();
                graphicView.cache(graphicView.bounds());

                undoManager.setActionName(GRID_OP);
        }






   Method[] methods = target.getClass().getDeclaredMethods();

   ...
}

protected Method getBestMatch(Class targetClass, Class[] argClasses) {
   Method[] methods = targetClass.getDeclaredMethods();
   ...
}

undoManager.registerUndoWithTarget(this, "setGridVisible", currentValue); Where the methods in the Java UndoManager could be implemented something like: public void registerUndoWithTarget(Object target, Method method, Object... args) public void registerUndoWithTarget(Object target, String methodName, Object... args) { Method method = getBestMatch(target.getClass(), getTypesOf(args)); // The Objective-C and Java versions of the user code look pretty similar. What aspects of the Objective-C undo manager am I missing?

I.e. this form:




b.bum

How would you support the more generically applicable invocation form in Java? [[NSUndoManager prepareWithInvocationTarget: self] setFrame: myRect animate: YES spline: splineStruct];

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