karlpet at mac.com
Mon Jul 8 12:22:00 EDT 2002
At 11:42 PM -0700 7/7/02, Dan Shafer wrote:
>Does RR have a true component model? One that would allow me, e.g.,
>to create a new *type* of component either by aggregating existing
>ones or by starting with an existing component, changing default
>properties and then saving it in a way that I could transparently
>use it in my RR apps?
Dan, check out the Object Library in the Development menu. It allows
you to install Rev-defined objects that ship in the Library, plus
install your own objects you've added to the Library. You can also
create new libraries you access via the Object Library.
It that's not exactly what you need, it's not difficult to create
your own custom object library that uses your own installer scripts.
Your script can refuse to install a field unless a group is selected
as its destination, for example.
Remember too that like HyperCard, Rev sends a new<Object> message to
a new object when it is created. (NewField, newButton, newImage, et.
al.) That lets you create very smart objects that can help install
themselves. They can even create/configure other objects around them.
Like you, I wanted a special field I could quickly install in new
stacks. I wanted it to know how to resize itself when the window size
changed and modify the appearance of its scrollbars when the stack is
suspended/resumed. (The field covers its scrollbars with buttons so
they look "disabled" like normal Mac OS scrollbars.) Responding to
the newField message it receives, the field creates the scrollbar
cover buttons it needs, saves their button IDs in a field property,
and installs a group script that broadcasts
resizeStack/suspend/resume messages to all objects in the group. When
done, the field also removes its own newField handlers.
A running field script can't perform certain tasks -- modify its own
script, for example -- but that can be accomplished by "sending" a
message to a group owner for execution a few milliseconds after the
field is installed.
Rev's custom properties are extremely useful here too. A property of
the field stores the group script, for example. When the field is
finished installing itself, it deletes all the custom properties it
no longer needs.
Note that the new<Object> message is NOT sent when you Paste an
object, so Copying and Pasting is limited to simpler objects. But
beyond that limitation, just about anything is possible.
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