[stringtemplate-interest] StringTemplate type proxies

[Terence Parr]

BTW, i believe "adaptor" is the right pattern name here right?  It's a specialized proxy used to adapt one lib to another.
Ter
On Dec 14, 2010, at 5:40 PM, Rafael Chaves wrote:

> Just to be clear, I meant one would register the decorator factory,
> not a single decorator.
> 
> In my implementation, it is up to the factory to decide whether to
> wrap/decorate or not -  it may choose to return the object it got
> "as-is" in some cases (i.e. not wrap it), for instance.
> 
> On Tue, Dec 14, 2010 at 12:22 PM, Rafael Chaves <rafael at alphasimple.com> wrote:
>> Yeah, I'd rather register an instance instead of passing in a class
>> and let ST instantiate it. That would address your concern about
>> efficiency, but it is just better design IMO.
>> 
>> On how to determine whether the wrapper should be activated, I'd hope
>> it would be based on an "instanceOf" match instead of an exact class
>> match (which is a grip I have with AttributeRenderer). I don't
>> necessarily know the classes of the objects I am dealing with
>> (implementation classes are often not exposed to clients of an API,
>> but I will know some public class or interface), or may be interested
>> in a hierarchy of classes. True, that leaves some room for multiple
>> wrappers being interested in the same object, but you can decide based
>> on order of registration (first or last to match wins) - for a single
>> template, it is reasonable to assume there is only on party involved.
>> 
>> Cheers,
>> 
>> Rafael
>> 
>> On Tue, Dec 14, 2010 at 12:06 PM, Terence Parr <parrt at cs.usfca.edu> wrote:
>>> Ah! You are so correct! It only works on the values you pass through setAttribute. Ok, so the proposition is to simply add
>>> 
>>> registerProxy(ModelType, MyProxyType)
>>> 
>>> and have ST created new MyProxyType object with
>>> 
>>> new MyProxyType(aModelTypeObjectAttribute)
>>> 
>>> for each reference to a ModelType object? Won't that get inefficient? perhaps it should be like renderer and we  create a single object to wrap any object?
>>> 
>>> $a.foo$ would invoke method MyProxyType.getFoo(a), right?
>>> 
>>> Am  I going in the right direction?
>>> 
>>> Ter
>>> 
>>> On Dec 14, 2010, at 11:28 AM, Rafael Chaves wrote:
>>> 
>>>> Yup, renderers translate from whatever values to String. The decorator
>>>> (not a proxy, as it augments the shape of the target object) allows
>>>> obtaining the values.
>>>> 
>>>> This should apply at any level in the model graph, not only top level
>>>> attributes. Does setAttribute handle that?
>>>> 
>>>> For instance: Package has Classes with have Attributes. I set only one
>>>> attribute on the top-level template, to be the root package object,
>>>> and then navigate the graph with several templates (one for packages,
>>>> one for classes, and another for attributes).
>>>> 
>>>> Will overriding setAttribute allow me to intercept how any arbitrarily
>>>> deep object is handled?
>>>> 
>>>> Cheers,
>>>> 
>>>> Rafael
>>>> 
>>>> On Tue, Dec 14, 2010 at 11:16 AM, Terence Parr <parrt at cs.usfca.edu> wrote:
>>>>> Very convincing argument, folks. thank you. 3rd party models.
>>>>> 
>>>>> Ok, so how do they interact with renderers?  I guess the renderer is done *after* proxy stuff.
>>>>> 
>>>>> Proxy: RandomModelObject -> MyWrapperForRandomModelObject, adds getFoo() or whatever.
>>>>> 
>>>>> Then, if getFoo() returns type Date, renderer applies to that.  I like it.
>>>>> 
>>>>> I remember mentioning how to do this manually. just override setAttribute() so that it traps RandomModelObject and wraps.
>>>>> 
>>>>> Does this need to be formalized or can it simply be a FAQ entry?  it's a switch on type, look up in hashtable thing only right?
>>>>> 
>>>>> Ter
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>>> 
>>> 
>> 
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