Adding new attribute type....

[Pawel Kozlowski <pk...@amadeus.com>]

Hi All,

First of all, thnx for all the hard work put in the Tiles2 development. 
It's good to see old, good library with refreshed API.

Speaking about the API: I was trying to add a new attribute type to Tiles2 
and I've found that this is not a trivial task? I mean, I can find all the 
places to tweak, but I'm a little bit scared of changing 
BasicTilesContainer. For me, the problems comes from the:

 public void render(Attribute attr, Writer writer, Object... requestItems)

method. More specifically, this switch statement is kind of problematic:

switch (type) {
            case OBJECT:
                throw new TilesException(
                    "Cannot insert an attribute of 'object' type");
            case STRING:
                writer.write(attr.getValue().toString());
                break;
            case DEFINITION:
                render(request, attr.getValue().toString());
                break;
            case TEMPLATE:
                request.dispatch(attr.getValue().toString());
                break;
            default: // should not happen
                throw new TilesException(
                        "Unrecognized type for attribute value "
                        + attr.getValue());
        }

It looks like I would need to change the AttributeType enum, definitions 
reader and the BasicTilesContainer? 

I was wondering if it would be possible to change an implementation in the 
way that each attribute is responsible for rendering itself. I know this 
is quite a change, but I was wondering if such a design was ever 
considered. Sorry if I'm blind and can't see obvious problems with such a 
design?. I would be really grateful for any feedback. Basically, my goal 
is to add a new type of attribute and not to rewrite to much chunks of 
Tiles2.

Thnx,
Pawel

Re: Adding new attribute type....

[Antonio Petrelli <an...@gmail.com>]

2007/6/11, Pawel Kozlowski <pk...@amadeus.com>:
> Speaking about the API: I was trying to add a new attribute type to Tiles2
> and I've found that this is not a trivial task?

In fact you cannot do it :-)

> I mean, I can find all the
> places to tweak, but I'm a little bit scared of changing
> BasicTilesContainer.

Why are you scared? I guess it doesn't bite :-) Jokes apart, what
exactly are going to accomplish? We can help you achieving your
objectives if you tell us what they are.

> I was wondering if it would be possible to change an implementation in the
> way that each attribute is responsible for rendering itself. I know this
> is quite a change, but I was wondering if such a design was ever
> considered.

I did not originally create the container, but I think that David (the
one that created it) thought about other frameworks. Correct me if I
am wrong, but, for example, in JSF the component does not render
itself, but a "renderer" renders it.

> Basically, my goal
> is to add a new type of attribute and not to rewrite to much chunks of
> Tiles2.

What is your attribute type and what does it represent?

Antonio