On Mar 19, 2008, at 8:25 AM, viktoras didziulis wrote:
I would like to define a class, an object (the both with their
properties) and methods that are not a part of graphical user
interface or Revolution engine...
Let's say I need an object "City" having properties: minLatitude,
maxLatitude, minLongitude, maxLongitude, area, populationSize,
growthRate, dateFounded, currentDate so it can be handled using
specific handlers and functions (e.g. its methods). Or, well, it
would be more correct to start with creation of a class "City" or
"templateCity" and then use it to create new "city" objects
(NewYork, Paris, etc...) that can be processed by their functions
like "populationGrowth(Paris, start_year, end_year)" and so on...
The three approaches that I can imagine are somehow inter-tangled:
(1) creating an object as a custom property set of a stack or (2)
creating it as an array or (3) creating it as an invisible control
with custom properties. But all these have their drawbacks.
Just some quick notes from methods I've tried. You probably won't find
any consensus on this since Rev does not have an elegant way of
extending the xtalk syntax to our own custom objects. Hopefully one
day...
1) This could work but I have found it easier to work with individual
objects. I just pass button references around to my "class" handlers.
See point 3 notes.
2) This can be useful in some circumstances but it is easier to
inspect the custom props of a button during debugging.
3) I prefer this approach. I create a stack that I use as a library. I
then create "classes" using handler prefixes:
put city.getProp (pLongIDofButton, "growth rate") into theGrowthRate
city.setProp pLongIDofButton, "growth rate", "1"
put city.Serialize (pLongIDofButton) into theSerializedCity
Each handler takes a reference to a button whose uObjectProps custom
property set represent the object properties. So calling city.getProp
would return the uObjectProps["growth rate"] custom property for
example. Calling city.setProp would set the uObjectProps["growth
rate"] value after having performed integrity checks.
I create buttons on hidden stacks or just hide the button itself on a
visible stack. Depends on my needs.
I prefer to define city.getProp/setProp handlers since I hate writing
out city.getGrowthRate, city.setGrowthRate every time I want to add a
new property.
I never use Revolution's getProp/setProp handlers when dealing with
custom objects unless they are GUI elements. getProp/setProp fails to
be called when messages are locked which is not very robust.
The (1) and (3) approach allows attaching handlers to custom
properties and allows accessing object (e.g. a custom property set)
properties using both an array notation (somehow an equivalent to an
array-like behavior of objects in javascript) and in a way
consistent with handling of properties in Rev e.g. "set the .. of ..
to ..." or "get .. the .. of ...". Unfortunately (1) allows only a
single object to be active and thus accessible. The (3) is a dirty
one, because object is created using empty controls with their own
additional properties and methods. The (2) looks promising, one can
create a class, write a constructor function that would create new
objects from the class, etc... But it lacks consistency with the
existing OOP style in Rev - e.g. you can not get or set an element
of an array using "get the <element/property> of <array/object>" or
"set the <element/property> of <array/object> to <value>". Besides
you can not use getProp or setProp handlers with array's elements.
Not being able to define our own objects that have the same elegant
syntax that is native to Rev is the real drawback.
Did anyone try doing something like this kind of OOP in Rev? I would
appreciate if you can share your thoughts, warnings, tricks and
approaches :-). I am not looking for a complex C++ like style of OOP
in Rev. Anything simpler like the OOP model of javascript would be
OK. In general, I think, it would be nice if one could treat and
access Revolution arrays as objects with custom properties, with all
the getProp, setProp and templateObject stuff... Or is it possible
somehow? If not, is this already posted to QC as an enhancement
request - I would vote for it? Otherwise going to post it there
myself...
Just some thoughts. I have tried a few different approaches myself and
the above is what I have settled on for the time being.
Regards,
--
Trevor DeVore
Blue Mango Learning Systems
www.bluemangolearning.com - www.screensteps.com
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