Getting Started
Parameter-from-action connections use the result of an action as a
parameter to a connection. This connection type can be used in very
powerful ways. To illustrate the use of this connection, we'll
introduce a new part called the Object Factory. As the name
implies, the Object Factory part creates new objects from an existing
model called a Class. In this case, the mold we
will use is the already familiar Ordered Collection. If you
remember, you used the Ordered Collection part to build the To-do List
sample. Refer to Working with nonvisual parts for the details related to the use of the Ordered
Collection part in the To-do List sample. An example of how to use a
parameter-from-action connection follows:
- Place a Push Button part and a List part within the default Window part in
the Composition Editor.
- Now, place an Ordered Collection part and an Object Factory part onto an
open area of the Composition Editor free-form surface. Both the Ordered
Collection part and the Object Factory part can be found in the Models
category of the Composition Editor.
- Bring up the property view for the Object Factory part by double-clicking
on it and set the instanceClass property value by typing in
OrderedCollection. Be sure to maintain the exact
case.
- Connect the clicked event of Push Button part to the
add: action of the Ordered Collection part.
- Then, make the parameter-from-action connection by connecting the
new action from the Object Factory part's Connect
menu to the anObject attribute in the connection's pop-up
menu. This provides the needed connection parameter and causes the
connection line to become solid in color.
- Finally, connect the self attribute of the Ordered Collection
to the items attribute of the list. This connection allows
us to prove the new instances of the OrderedCollection are indeed created by
displaying the results in a list part.
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