On 05.05.2009, at 07:27, Milan Zimmermann wrote:

  

On May 4, 2009, Bert Freudenberg wrote:
    

On 04.05.2009, at 07:31, Milan Zimmermann wrote:
      

Hi Bert,

I finally did some investigation into Squeak interaction with  
        

DBus and
    

Datastore. I went through the classes that implement the DBus and
Datastore
interaction. This is some great stuff! Among others, if I  
        

understand
    

this correctly, your Squeak DBus client framework could, for
example, allow to use Squeak to write a KDE or gnome panel applet?
But that is an aside.
        

Yes indeed.
      

Very cool. I think such functionality could also add interest in  
Squeak... Would it makes sense to add Squeak to this list

http://www.freedesktop.org/wiki/Software/DBusBindings
?
    

Yes. This would be the official page for it:

http://squeaksource.com/dbus.html

  

A fun way to explore it is to run Squeak on a regular KDE/
Gnome desktop and open the DBus Explorer from the World menu. You  
      

can,
    

for example, find the screen saver on the session bus and tell it to
blank the screen ...
      

Or exiting any application :) This is worth a blog by itself.
    

Oh, nice idea. Announce it on squeak-dev, too. And maybe have your  
blog (or the posts tagged with "squeak") added to planet.squeak.org ...

  

World Menu -> Open -> DbusExplorer.
Expand DBus sessionBus
open KDE system konsole
org.kde.konsole/konsole/MainWindow_1/actions/file_quit/
com.Trolltech.QT.QAction.trigger
yellow(middle or right)-click, select "invoke method"
konsole gone
Neat...
    

Hehe. Did you notice you can even invoke methods with arguments?

  

Well. IMHO we should *not* save the whole project to the Journal.  
      

This
    

is not supposed to be an Etoys activity, but a Squeak application.  
      

It
    

should only store and retrieve its relevant state. For starters I'd
only store the statistics, which is about 10 numbers.
      

I did not think of saving only the state of the game, but it is  
definitely a better approach. Maybe I am missing something here  
though. For example, in Etoys, saving a project writes the whole  
project as a pr file - I assume .PR is some for of serialized  
everything in the project, not just what have changed.
    

Yes, it writes out pretty much everything reachable from "Project  
current".

  

When attempting to store only FreeCell's state, I have a few things  
to learn and understand:
- without looking I am surptised FreeCell's state is only 10  
numbers, it seems that position of the cards must be more than that  
unless it's packed somehow - I will look
    

No, that is only the statistics. Not sure how useful it is to store  
the entire state.

  

- which objects represent the state stored
- how to serialize it (well that should be relatively  
straightforward knowing the objects)
- what method will write the serialized FreeCell state to Journal
instead of  
SugarDatastoreDirectory>>#writeProjectinFileNamed:fromDirectory:
    

In FreeCell.st I patch SugarLauncher>>quit which normally would store  
the project, so nothing is stored but the activity simply quits.

This is triggered either by pressing the stop button in the tool bar,  
or by a #windowClose event the launcher receives because in its  
#startUp method it registered itself for these events:

	World windowEventHandler: self.

So if we replace the SugarLauncher mechanism we should register these  
events to be sent to FreeCell instead.

  

- what does assign the "ownership" of that file on Journal as FreeCell
    

Just the meta data properties, in particular the "activity" property.  
See

http://wiki.laptop.org/go/Low-level_Activity_API#Meta_Data

  

- how to deserialize the state
- how to import it back to the game


    

The regular Etoys Sugar startup happens in SugarLauncher>>startUp.
      

yes

    

There it looks for the ACTIVITY_ID parameter to see if we are  
      

actually
    

running under Sugar, and an OBJECT_ID which is present if we are
resuming a Journal entry.
      

yes

    

I think the best way would be to use different parameter names in
FreeCell.sh, perhaps FREECELL_ACTIVITY_ID and FREECELL_OBJECT_ID.  
      

Then
    

the Etoys logic would not kick off
      

logic in SugarLauncher.startup?
    

Yes, because that looks for ACTIVITY_ID and OBJECT_ID.

  

and would not try to open the
object as project, but we could provide our own startup method  
      

that we
    

would simply call at the end of FreeCell.st.
      

and load the state read from the Datastore/Journal?
    

Right, if the FREECELL_OBJECT_ID parameter is present it would hold  
the object id to load.

  

4) Ability to start using the black Launcher ribbon on top, with  
        

the
    

standard Etoys project name a project stop widget that would call
the commands from 1 and 2. .
        

Well if you look at the end of FreeCell.st you see the tool bar is
explicitly toggled off. Before re-enabling it we would have to
customize it (see class SugarNavigatorBar).
      

Ah I thought the bar was SugarLauncher. Another thing to look at.
    

No, SugarLauncher is registered with the AutoStart class, just like  
the ProjectLauncher which handles the regular Etoys startup (like  
loading a project in the browser plugin etc.).

SugarLauncher handles all the Sugar-related session tasks - datastore,  
collaboration, etc. It's not a pure launcher anymore and probably  
should be factored into some more specific classes.

  

I am actually quite excited about this - you did lots of great stuff  
there that deserves attention, use, and maybe we can do some  
marketing for it :) by having a few blogs and a small tutorial at  
some point. Long time ago I played with DCOP in KDE and Dbus is  
similar but that's not the point - The point is that apart from it's  
usefulness for Sugar, what you did can be also used for Squeak /  
Etoys applications to be integral part of KDE and Gnome desktops  
(perhaps even OS X - I am reading Dbus is ported there there but  
probably not integrated). I especially like the idea trying to write  
a KDE Panel applet in Squeak :)
    

Sounds like a fun thing to try, yes :)

- Bert -