Re: [xtext-dev] add visitor method to generated AbstractElement interfac

[Jan Köhnlein <jan.koehnlein@xxxxxxxxx>]

Hi Michael,

I reply for Sven as he's so busy:

You can use the generated EMF switches (XtextutilSwitch,  
ParsetreeSwitch or XtextSwitch) to implement multi-methods (dynamic  
dispatch) for Ecore models and avoid repetitive usage of "instanceof".  
The switch classes simply implement a visitor pattern. Inherit from  
the generated abstract class and override the "caseXXX" methods to  
return type specific values. Use doSwitch() to call the type specific  
function.

The switch internally uses the much better performing EClass IDs from  
the EPackage instead of "instanceof". It also takes care of  
inheritance by switching to the superclass if there is no result.

Sorry, I don't have an example at hand, but feel free to ask again if  
this information is not sufficient.

Regards
Jan




Am 15.09.2008 um 10:32 schrieb michael clay:

> hi sven,
>
> could you point me in the right direction pls. did you mean
> XtextutilSwitch,ParsetreeSwitch or XtextSwitch
> do you have an example code to showcase the usage of the 'generated
> switch' class to examine if its sufficient?
>
>
> m
>
> On Mon, Sep 15, 2008 at 10:24 AM, Sven Efftinge <sven@xxxxxxxxxxx>  
> wrote:
> > Hi Michael,
> >
> > you could use the generated Switch class to do that.
> > Would that be sufficient?
> >
> > Sven
> >
> > On Sep 14, 2008, at 8:13 PM, michael clay wrote:
> >
> > > hi all,
> > >
> > > i would like to add a visitor method (@modified) to the generated  
> > > EMF
> > > AbstractElement interface to  get rid of the various 'instanceof'  
> > > test
> > > in several places of the xtext code for a cleaner
> > > structuring and better maintainability of the code base.
> > >
> > > pls. let me know if this is ok for you.
> > >
> > > thx
> > > m
> > > _______________________________________________
> > > xtext-dev mailing list
> > > xtext-dev@xxxxxxxxxxx
> > > https://dev.eclipse.org/mailman/listinfo/xtext-dev
> >
> > _______________________________________________
> > xtext-dev mailing list
> > xtext-dev@xxxxxxxxxxx
> > https://dev.eclipse.org/mailman/listinfo/xtext-dev
> _______________________________________________
> xtext-dev mailing list
> xtext-dev@xxxxxxxxxxx
> https://dev.eclipse.org/mailman/listinfo/xtext-dev

--
Dr. Jan Köhnlein
Senior Software Architekt

Telefon: +49 (0) 431 / 5606-337
Mobile: +49 (0) 163 / 3979 776
Telefax: +49 (0) 431 / 5606-339

http://www.itemis.de
jan.koehnlein@xxxxxxxxx

itemis AG
Schauenburgerstr. 116
24118 Kiel

Rechtlicher Hinweis:

Amtsgericht Dortmund, HRB 20621

Vorstand: Wolfgang Neuhaus, Jens Wagener, Dr. Georg Pietrek

Aufsichtsrat: Prof. Dr. Burkhart Igel (Vors.) Stephan Grollmann,  
Michael Neuhaus