[FreeCiv-Java] Re: Events

["Brian Duff" <Brian.Duff@xxxxxxxxxx>]

Hi Alex,

You're absolutely right, there is a distinct lack of eventing in some areas
of the code. At the moment, the handlers tend to call methods to update
things after they've been updated. I would really like to sort this out,
because it's bad programming practice and means that many methods on the
Client have visibility that really shouldn't. It was written this way,
because that's pretty much how the C client works. But it's less than ideal.

Hopefully, we can eventually add event code to the "data" classes in
org.freeciv.common for notification when objects get changed, or when items
get added or removed from lists (e.g. a city's name changes, a new unit is
added to the supported list of a city). This will go a great way towards
making the code neater and more object oriented.

At the moment, there are a large number of Action implementations in the
org.freeciv.client.action package. These make up the core of the
user-invokable events: anything that can be done through the UI. These
classes all implement ActionListener (Action is derived from it), so can be
easily plugged in to buttons and other controls. For each class of action, a
single instance is maintained by the Client: you can obtain the instance for
any given action using

clientInstance.getAction( Class actionClass )

where actionClass is the class for the action you want to retrieve.

For the console window, the best thing might be to define an action along
the lines of ACTSendConsoleMessage, then add it as an actionlistener to the
Console. There might be some issues with the order in which listeners get
added; I seem to remember that Console already adds a listener internally,
to clear the field after the user presses Enter. We'd want this to happen
after the console message action was fired. For this reason, probably the
best way to implement it is to add

addActionListener()
removeActionListener()

methods to Console, then have the client or main window actually register
the ACTSendConsoleMessage action with the Console. Then Console can use its
own internal action listener to ensure its field clearing happens after
firing the action event out to listeners added to Console.

Anyway, let me know if this helps, or if I've gone off on the wrong track
entirely..

Thanks,

Brian

-----Original Message-----
From: freeciv-java-bounce@xxxxxxxxxxx
[mailto:freeciv-java-bounce@xxxxxxxxxxx]On Behalf Of Alexander Braun
Sent: 09 November 2001 19:34
To: jFreeCiv
Subject: [FreeCiv-Java] Events


Dear all,

I just started looking at the code in earnest, and after about close to
three hours of looking (read: staring) at it I start to see a pattern
emerging :-) _But_ as far as I see it there's no dedicated class handling
the action events?! Or I didn't see it yet :-) Actually I'd like to stick to
the facts: I was thinking of implementing the chat line, because that seemed
like an easy start. And for _that_ (i.e. the client.panel.Console) I didn't
see an action handler sign up. And then the question arises: _where_ do we
handle events?

Normally I would have said in the main GUI class (ie. client.MainWindow) but
as the client.Client class manages the lot on second thought it should be
going there. And, then again, inner classes wouldn't be to bad either,
especially with the many components floating around, some of them (like the
MapOverview) quite complex.

If this seems like a trivial question then sorry for that. At least for the
Console it seems straightforward to simply use inner classes. But I guess
there's a lot more going on which I don't see yet, and I can well imagine
lot's of events hopping around without proper handling.

Again, if this is trivia, I'd be glad if someone pointed out the obvious to
me. If not it seems we should have a short discussion to agree on the matter
of what gets handled where.

Thanks,

Alex
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