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Posted to users@cocoon.apache.org by Daniel McOrmond <dm...@gmail.com> on 2005/02/22 17:10:18 UTC
Java Class Casting within Flow
Here's a simple example:
importClass( Packages.com.company.GenericObject );
importClass( Packages.com.company.SpecificObject );
importClass( Packages.com.company.ObjectLoaderUtil );
function doSomethingUseful() {
var loader = cocoon.createObject( ObjectLoaderUtil );
var myObject = loader.getGenericObject();
}
Suppose I wanted to cast the GenericObject to a SpecificObject, like this:
var myObject = (SpecificObject) loader.getGenericObject();
Obviously there are other ways I could handle this. But I just
wondered, is there a way to do this within flow?
-Daniel
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Re: Java Class Casting within Flow
Posted by Brian Vargas <ar...@procrastinators.org>.
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Daniel and Leszek,
> AFAIU rhino (flowscript engine) uses reflection to resolve methods and
> fields. It doesn't really matter that you pass some narrow interface
> because reflection will expose full underlying object functionality.
Rhino is an implementation of ECMAScript (a.k.a JavaScript). Such
casting is not necessary because ECMAScript is not a statically-typed
language. The Rhino implemenation is capable of wrapping plain old Java
objects and exposing them as script objects, almost certainly using
reflection.
You should check out the spec some time. It's a boring read, but some
of the higher-level things you can do with ECMAScript are really cool.
http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf
Brian
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Re: Java Class Casting within Flow
Posted by Leszek Gawron <lg...@apache.org>.
Daniel McOrmond wrote:
> Just a follow up on this thread. I tried Leszek's solution again and
> it worked properly. I suspect that I most likely misspelled something
> on my first attempt!
>
> Thanks for your help. When I get a chance, I'm going to dig in and
> figure out exactly _how_ that works.
AFAIU rhino (flowscript engine) uses reflection to resolve methods and
fields. It doesn't really matter that you pass some narrow interface
because reflection will expose full underlying object functionality.
--
Leszek Gawron MobileBox
lgawron@apache.org http://www.mobilebox.pl
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Re: Java Class Casting within Flow
Posted by Daniel McOrmond <dm...@gmail.com>.
Just a follow up on this thread. I tried Leszek's solution again and
it worked properly. I suspect that I most likely misspelled something
on my first attempt!
Thanks for your help. When I get a chance, I'm going to dig in and
figure out exactly _how_ that works.
-Daniel
On Tue, 22 Feb 2005 11:34:31 -0500, Daniel McOrmond <dm...@gmail.com> wrote:
> Hmm. I would be interested to understand why you suggest that?
>
> In this case the SpecificObject has additional methods not contained
> in the GenericObject. When I try to call those methods, Flow complains
> ( as I expect ) that the method is not available.
>
> -Daniel
>
>
> On Tue, 22 Feb 2005 17:25:20 +0100, Leszek Gawron <lg...@mobilebox.pl> wrote:
> >
> > you do not need a cast - just call SpecificObject methods.
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Re: Java Class Casting within Flow
Posted by Daniel McOrmond <dm...@gmail.com>.
Hmm. I would be interested to understand why you suggest that?
In this case the SpecificObject has additional methods not contained
in the GenericObject. When I try to call those methods, Flow complains
( as I expect ) that the method is not available.
-Daniel
On Tue, 22 Feb 2005 17:25:20 +0100, Leszek Gawron <lg...@mobilebox.pl> wrote:
>
> you do not need a cast - just call SpecificObject methods.
>
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Re: Java Class Casting within Flow
Posted by Leszek Gawron <lg...@mobilebox.pl>.
Daniel McOrmond wrote:
> Here's a simple example:
>
>
> importClass( Packages.com.company.GenericObject );
> importClass( Packages.com.company.SpecificObject );
> importClass( Packages.com.company.ObjectLoaderUtil );
>
> function doSomethingUseful() {
> var loader = cocoon.createObject( ObjectLoaderUtil );
> var myObject = loader.getGenericObject();
> }
>
>
>
> Suppose I wanted to cast the GenericObject to a SpecificObject, like this:
>
> var myObject = (SpecificObject) loader.getGenericObject();
you do not need a cast - just call SpecificObject methods.
--
Leszek Gawron lgawron@mobilebox.pl
Project Manager MobileBox sp. z o.o.
+48 (61) 855 06 67 http://www.mobilebox.pl
mobile: +48 (501) 720 812 fax: +48 (61) 853 29 65
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