Q: type conversion with Gdome

Q: type conversion with Gdome

[Yang Shouxun]

Hello everyone,

I've been using Gdome for some time now and I always find it difficult to deal 
with the type system. Here is the issue:

The document class has a
 method getElementsByTagName :
      tagname:Gdome.domString -> Gdome.nodeList
and from a nodeList object I can only get Gdome.node objects, while we know 
they should be Gdome.element objects.

My question is how to convert from Gdome.node to Gdome.element? 

P.S. Gdome.element can be converted to Gdome.node, but not in the other 
direction as far as I know.

TIA,

shouxun

Re: [Caml-list] Q: type conversion with Gdome

[Claudio Sacerdoti Coen]

Dear Yang,

not every node is an element. Thus you need to use dinamic cast:

let node = ... in
  (* next line may raise GdomeInit.DOMCastException *)
let element = Gdome.element_of_node node in
  ...

						Cheers,
						C.S.C.

On Wed, 2008-07-16 at 17:13 +0800, Yang Shouxun wrote:
> Hello everyone,
> 
> I've been using Gdome for some time now and I always find it difficult to deal 
> with the type system. Here is the issue:
> 
> The document class has a
>  method getElementsByTagName :
>       tagname:Gdome.domString -> Gdome.nodeList
> and from a nodeList object I can only get Gdome.node objects, while we know 
> they should be Gdome.element objects.
> 
> My question is how to convert from Gdome.node to Gdome.element? 
> 
> P.S. Gdome.element can be converted to Gdome.node, but not in the other 
> direction as far as I know.
> 
> TIA,
> 
> shouxun
> 
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-- 
----------------------------------------------------------------
Real name: Claudio Sacerdoti Coen
Doctor in Computer Science, University of Bologna
E-mail: sacerdot@cs.unibo.it
http://www.cs.unibo.it/~sacerdot
----------------------------------------------------------------

Re: [Caml-list] Q: type conversion with Gdome

[Yang Shouxun]

On Wednesday 16 July 2008 17:44:18 Claudio Sacerdoti Coen wrote:
> Dear Yang,
>
> not every node is an element. Thus you need to use dinamic cast:
>
> let node = ... in
>   (* next line may raise GdomeInit.DOMCastException *)
> let element = Gdome.element_of_node node in
>   ...

Thank you very much. I haven't noticed element_of_node. As 
Gdome.element_of_node is a class and there is no equivalent function, thus my 
final version is like is:

let element = new Gdnome.element_of_node node in

> 						Cheers,
> 						C.S.C.
> On Wed, 2008-07-16 at 17:13 +0800, Yang Shouxun wrote:
> > Hello everyone,
> >
> > I've been using Gdome for some time now and I always find it difficult to
> > deal with the type system. Here is the issue:
> >
> > The document class has a
> >  method getElementsByTagName :
> >       tagname:Gdome.domString -> Gdome.nodeList
> > and from a nodeList object I can only get Gdome.node objects, while we
> > know they should be Gdome.element objects.
> >
> > My question is how to convert from Gdome.node to Gdome.element?
> >
> > P.S. Gdome.element can be converted to Gdome.node, but not in the other
> > direction as far as I know.
> >
> > TIA,
> >
> > shouxun