On Tue, Sep 6, 2011 at 9:39 AM, Simone Tripodi <[email protected]> wrote:
> Hi Niall,
> thanks for the hint!
>
> Anyway (DISCLAIMER: I'm putting in the original chain author's shoes,
> so I couldn't say the truth) I immagine that users would be interested
> on having, as a Context, not just a place where storing computed
> element to be shared between chain commands, but having also the
> possibility of customizations adding, for example, shared clever
> methods - take a look at the concrete default
> {{org.apache.commons.chain.impl.ContextBase}} implementation where
> there is an index of PropertiesDescriptors.
I understand what Chain does - I was the last active Chain committer.
I was also around when it was developed for Struts.
You miss the point I make though. Context is currently an interface
that extends the Map interface - it adds nothing, zilch, nada, rien to
the Map interface
public interface Context extends Map {
}
So the only thing having "Context" does is it prevents use of any
standard Map implementation. It doesn't prevent any fancy or clever
implementations you want to create - but just restricts what you can
pass through the Chain.
Also I just looked at your changes to the Context definition and
you're now adding a second restriction - that the keys to the Context
have to now be a String. Thats great for people who effectively want a
property name - but its a new limitation for those that don't and I
don't see any benefit to that limitation.
Niall
> Honestly thinking, after raw your message, I'd tend to agree that
> Map<String,Object> would be more than enough - just for the record,
> that's what we deed indeed in the Apache Cocoon3 Pipeline APIs - but
> at the same time I like the idea of having dedicated Chain API as
> shown in the current implementation.
>
> Hard to take a decision...
> Simo
>
> http://people.apache.org/~simonetripodi/
> http://www.99soft.org/
>
>
>
> On Tue, Sep 6, 2011 at 2:19 AM, Niall Pemberton
> <[email protected]> wrote:
>> On Mon, Sep 5, 2011 at 12:21 PM, James Carman
>> <[email protected]> wrote:
>>> I agree with Paul here. Extending Map (or any other class for that
>>> matter) when what you really want to do is encapsulate it is silly.
>>> Is the Context really meant to be used in any place where a Map can be
>>> used? I would think not.
>>
>> I always thought the other way. I never understood why context wasn't
>> just a Map, rather than a new Chain specific type extending Map.
>>
>> Using Map has its advantages. Firstly the contract it provides besides
>> get/put are useful operations on the context (containsKey(), size(),
>> entrySet() etc.etc) , secondly (if it was a "plain" Map) there are
>> standard implementations & wrappers that can be used giving features
>> such as concurrency, ready-only etc. and thirdly tools & libraries
>> understand how to operate on a Map.
>>
>> Niall
>>
>>> On Sun, Sep 4, 2011 at 11:54 PM, Paul Benedict <[email protected]> wrote:
>>>> I want to get rid of it extending map. Have it define as asMap()
>>>> function instead. Especially since JDK 8 is bringing in extension
>>>> methods, which adds new (and default) methods to all collections, it
>>>> won't look very nice. Let's make a break now.
>>>>
>>>> On Sun, Sep 4, 2011 at 9:20 PM, Raman Gupta <[email protected]>
>>>> wrote:
>>>>> On 09/04/2011 04:00 PM, James Carman wrote:
>>>>>> On Sun, Sep 4, 2011 at 3:44 PM, Simone Tripodi
>>>>>> <[email protected]> wrote:
>>>>>>>
>>>>>>> That is able to 'auto-cast' the retrieved object while Map#get() not.
>>>>>>>
>>>>>>
>>>>>> I believe the feature is actually called "type inference", not
>>>>>> "auto-cast." :)
>>>>>
>>>>> Thanks for the explanation... I see now that via the generic method
>>>>> the compiler infers the return type from the assignment type.
>>>>>
>>>>> Cheers,
>>>>> Raman
>>>>>
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