From: Joe Van Dyk <joe.vandyk@...>
Date: 2004-11-13T07:33:26+09:00
Subject: Re: Another design question...

Zach Dennis wrote:
> Joe Van Dyk wrote:
>
>> If you remember my previous post titled "automatically
>> call function on attribute set", you'll remember that I
>> have an airplane class and a airplane_drawing class,
>> which represents the airplane when drawn on the screen.
>>
>> I'm using GTK for this, by the way.
>>
>> Say the user right clicks on the airplane_drawing
>> object.  I want a menu to popup on the screen with
>> options that when selected will call methods on the
>> airplane object.
>>
>> Information on the airplanes is also listed in table
>> form, which reports each airplane's position, velocity,
>> etc.  When I right click on the row that represents the
>> airplane, I'd like the same popup menu (for now, perhaps
>> it will be different in the future) to pop up with
>> options that when selected will call a method on the
>> airplane object.
>>
>> Question:  Since the popup menu has pretty common
>> functionality between the graphical airplane display and
>> the table airplane display, what would be a good way to
>> generalize this?  Any patterns that would be useful
>> here?
>>
>>
>>
> For now you say you want the same pop-up menu (meaning
> same functionality?). If this is the case, make a
> Singleton class that represents your popup window and
> it's functionality.
>
> If your airplane_drawing and your table will utilize
> *most* of the same functionality then still use a
> Singleton, and allow it to be passed parameters which act
> as switches. These switches could depict what
> functionality shows up.
>
> Conceptually speaking maybe something like:
>
> #singleton
> class AirplanePopupMenu
>     @instance
>
>     #constants
>     AP_VELOCITY = 1
>     AP_LOCATION = 2
>     AP_SIZE = 3
>     AP_FUEL = 4
>     AP_WEIGHT = 5
>     #etc...
>
>     def get_instance
>        @instance
>     end
>
>     def show_menu( *args )
>        #Loop through arrat args which should correspond
> to the AP_xxx constants we specified
>        #  above. Depending on the switch then build the
> rest of your popup menu before displaying it
>        #  This way users of the AirpanPopupMenu could
> only utilize the functionality they want
>     end
>
> end
>
>
> Hope I didn't muddy the waters...
>
> Zach

How would the AirplanePopupMenu object know what Airplane object's method to
use when the user selects an item from the popup menu?