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Esteban Lorenzano | 25 Aug 22:37

child in PRAddCommand question

Hi,
I'm using pier in a project who needs execute certain operations after 
a command is executed (journal/persistence stuff) and I added a method 
PRCommand, who is executed after doExecute... so... what is the 
problem? well, I have to mark an object as "persistent", in 
PRAddCommand, and then I do: self child bePersistent... but, as #child 
answer a ew instance of #type, the operation is lost...
I changed #child to use an instVar and just instantiate once.... 
everything seems to be working now, but I want to know if there is a 
possible problem with this change...
what do you think? the change works?

Thanks,
Esteban

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Matthias Berth | 26 Aug 12:48

Re: child in PRAddCommand question

Hi Esteban,

just to clarify what your question is about:

You want to do certain operations after a PRCommand was executed,
right? So I wonder why you don't do them in the command's doExecute
method...

Now, in order to do stuff after executing the command,  you added a
method like doPostExecute to PRCommand, and you hooked that into the
execution logic defined in PRCommand, right?

Your problem is that you execute a PRAddCommand and you want to tell
the new child somehow to bePersistent. And you don't know how to do
that except for going into PRAddCommand and changing methods there.
The more general question is: how do I access the new child that is
created by a PRAddCommand, after it is created.

Am I understanding the problem correctly?

Maybe you can use a subclass of PRAddCommand that overrides
#doValidate, or #validateChild:in: ?

BTW: as far as I understand Piers design, persistency is supposed to
be managed by the Pier kernel: PRCommand>>execute says self kernel
persistency execute: self.

Cheers

Matthias
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Lukas Renggli | 26 Aug 12:55
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Re: child in PRAddCommand question

> BTW: as far as I understand Piers design, persistency is supposed to
> be managed by the Pier kernel: PRCommand>>execute says self kernel
> persistency execute: self.

Yeah, if you need to know about executed commands then create your own  
persistency strategy and override #apply:. This can also be a simple  
delegator, that passes all requests to the default strategy and  
handles certain cases differently.

Cheers,
Lukas

--

-- 
Lukas Renggli
http://www.lukas-renggli.ch

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Esteban Lorenzano | 26 Aug 13:59

Re: child in PRAddCommand question

On 2008-08-26 07:55:36 -0300, Lukas Renggli <renggli <at> iam.unibe.ch> said:

>> BTW: as far as I understand Piers design, persistency is supposed to
>> be managed by the Pier kernel: PRCommand>>execute says self kernel
>> persistency execute: self.
> 
> Yeah, if you need to know about executed commands then create your own
> persistency strategy and override #apply:. This can also be a simple
> delegator, that passes all requests to the default strategy and
> handles certain cases differently.

Yes, that's exactly what I did... the problem is with PRAddCommand, 
because it creates the new child every time #child is called, then I am 
not working in the instance I saved but in a new one, that's why I want 
to change #child implementation, to keep the first instance it creates.

> 
> Cheers,
> Lukas

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Gmane