Lukas Renggli wrote:
>>>> I am struggling to write a command which edits a model, rather than
>>>> the
>>>> command instance itself. I am trying to do it this way since the
>>>> model
>>>> class and description may change whereas the command class does not.
>>>>
>>>>
>>> Why do you use a command then? As described in the GOF book, this
>>> design pattern is used to encapsulate an action and its parameters.
>>>
>> It does encapsulate an action. The problem being that commands as they
>> are can only act upon themselves.
>>
>
> Why do you think that? All commands I know act on other objects,
> mostly on structures in Pier.
>
> Cheers,
> Lukas
>
I must choose my words more carefully: they can only display themselves,
since the value returned from the component must be a command or nil.
Here is my solution....
PRContentsWidget-i-buildComponent: aContext
^ aContext command asComponent
onAnswer: [ :value | aContext command onAnswerValue: value to:
self ];
yourself
PRCommand-i-onAnswerValue: componentReturnValue to: widget
"componentReturnValue is typically but not necessarily a command"
componentReturnValue isNil
ifTrue: [ ^ widget context: (widget context structure: widget
context structure) ].
[ componentReturnValue execute ]
on: Error
do: [ :err |
Preferences debugPierFormErrors ifTrue: [ err pass ].
^ widget component errors add: err. ].
widget context: componentReturnValue answer
=========
what do you think?
Keith
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