[Newbies] How do you find which code runs when you click on something?

[Jerome Peace]

***
Hi Ian,
 
This is an excellent question ‘cause it shows up the
current obscurity of the answer.

The secret you need to know its that the object that
dispatches the mouse events looks high and low for
someone to handle it. When an unspecial morph is
clicked on the fellow who handles it is the paste up
morph that holds the morph.  The pasteup morph usually
lifts the morph and puts it in the hand, which then
moves it and eventually drops it somewhere.

So check out PasteUpMorph>>mouseDown: etc.

The second useful secret to know is that you can make
a morph special by going to its menu and giving it a
mouseUp action. Then the morph is highlighted when the
mouse is over it and pressing the mouse will prime and
the action which will happen if the mouse is released
while you are still in the object.

Or...
The third useful secret is you can make a morph
special by giving 
on: #mouseDown send: #selector to: anObject with:
argument
works also for #mouseUp and mouseMove and a bunch of
other things.
The special morph now has an EventHandler which gets
first crack at events before the PasteUpMorph of the
first secret.

look at the implementers and senders of #on:send: ...

Or...
The last not so useful secret is you could try to
write handlers to make your morph special. This is not
so useful because it takes full understanding of a lot
of subtleties. And if you can actually understand what
you are doing you will probably get distracted in
fixing the bugs you will run across.

For this look at morphs that have their own handlers
and imitate.

You are usually best off working with secret three.

Yours in curiosity and service, --Jerome Peace

> 
> 
> 
> 
> [Newbies] How do you find which code runs when you
> click on something?
> 
> 
> Matthew Fulmer tapplek at gmail.com 
> Wed Jun 27 00:26:41 UTC 2007 
> 
> 
> On Tue, Jun 26, 2007 at 09:47:29PM +0100, Ian
Oversby
> wrote:
> >Hi,
> >
> >I'm trying to find out which code is run when I
click
> on something
> >in Squeak.  I've tried selecting the menu from the
> middle button
> >and then selecting debug ->explore morph.  Is this
> the best
> >way?  Does it work for all morphs?  How can I add
new
> menu
> >items which run arbitrary code?
> 
> I tried exploring the morph, and also browsing the
class
> protocol (select the object in the
inspector/explorer,
> and press
> cmd-p). I limited the inheritance chain to
StringMorph,
> and
> examined the "event handlers" method category. I
looked
> at the
> mouseUp handler (mouse up is the usual place where
> actions are
> invoked), and the last line looked promising: "self
> invokeWithEvent: t1". I highlighted that and pressed
> cmd-m to
> jump to that method. The last few lines looked like
the
> real
> work. So I put a "self halt." right above the Cursor
> normal
> showWhile: [...] block and saved (cmd-s). Now,
whenever
> I hit a
> menu item, I get a debugger ready to execute the
menu
> command.
> 
> Whenever you are done, hit any menu item, remove the
> "self
> halt." in the debugger window, save, and proceed.
> 
> Hope that helps.
> 
> -- 
> Matthew Fulmer -- http://mtfulmer.wordpress.com/
> Help improve Squeak Documentation:
> http://wiki.squeak.org/squeak/808
> 
***



       
____________________________________________________________________________________
Pinpoint customers who are looking for what you sell. 
http://searchmarketing.yahoo.com/