21 Sep
2008
21 Sep
'08
6:24 p.m.
Doru I think that what I want this is graph traversal that I can
specialize
and the state of the traversing action should be stored into the model
so in a visitor.
Stef
On Sep 21, 2008, at 1:04 PM, Tudor Girba wrote:
It's not that I do not know what a visitor is, I
was just curious of
the use case, given that we have done quite a bit of things without
one :).
I believe that most Visitors can be nicely implemented using class
extensions. Of course, when you have a tree and a very complex
algorithm with many variation points, then having a visitor does
improve the situation. But even then, there is no reason for not
exposing the service as an extension method that then calls the
visitor. This makes life much easier for the client because there is
no need to know how to instantiate the visitor.
Cheers,
Doru
On Sep 21, 2008, at 12:44 PM, Stéphane Ducasse wrote:
Yes exactly and I would like to use the
importingContext of specify
how to filter
the model but in a conistent manner.
Stef
On Sep 21, 2008, at 11:33 AM, Oscar Nierstrasz wrote:
--
www.tudorgirba.com
www.tudorgirba.com/blog
"Be rather willing to give than demanding to get."
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Well, if a visitor has to implement many visit methods, but not all
visitors need to do something for visitable items, then it is handy
to
have a default visitor that implements all the visit methods with
empty bodies. You then simply subclass this default visitor and
override the few visit methods that you need.
There is an example in the compiler construction course.
https://www.iam.unibe.ch/scg/svn_repos/Lectures/CompilerConstruction/04Pars…
https://www.iam.unibe.ch/scg/svn_repos/Lectures/CompilerConstruction/Exampl…
Cheers,
- on
On Sep 20, 2008, at 23:33, Tudor Girba wrote:
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I am curious about the use case. Could you
elaborate a bit on this
one?
Cheers,
Doru
On Sep 18, 2008, at 1:18 PM, Oscar Nierstrasz wrote:
>
> I guess you mean a default visitor with empty visit methods that
> can
> be subclassed?
>
> Yeah, we need that.
>
> - on
>
> On Sep 18, 2008, at 13:09, stéphane ducasse wrote:
>
>> Hi guys
>>
>> We are looking for a model walker (visitor).
>> Does any one of you already implement one?
>>
>> Stef
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