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From Paul Benedict <pbened...@apache.org>
Subject Re: [chain][v2] clever context
Date Fri, 09 Sep 2011 20:20:37 GMT
On Fri, Sep 9, 2011 at 3:15 PM, Elijah Zupancic <elijah@zupancic.name> wrote:
> Specifying Object for V would be the most likely use case.
>
> On Fri, Sep 9, 2011 at 1:12 PM, Paul Benedict <pbenedict@apache.org> wrote:
>> On Fri, Sep 9, 2011 at 3:06 PM, Simone Tripodi <simonetripodi@apache.org> wrote:
>>> Hi Paul,
>>> the use of that method is to automatically infer the assigned type,
>>> instead of writing
>>>
>>>    MyPojo myPojo = (MyPojo) context.get( "myKey" );
>>>
>>> the retrieve method allows to
>>>
>>>    MyPojo myPojo = context.retrieve( "myKey" );
>>>
>>
>> Hmm... The inference should be automatic unless you specified Object for type V:
>> Context<String, String> properties = new ContextBase<String, String>();
>> String value = properties.retrieve("myKey");
>>

I don't have a good answer for the problem. I just think if you
declare types <K, V> at the class level, those should be the types
used on the methods too. The problem that I have with <T extends V> is
that it assumes a type-safe cast. You are right to say
ClassCastException was thrown for both of your examples but <T extends
V> breaks the "rule" that generics should be type-safe casts. It's
better to have the user create a bum cast and fail then the compiler
infer a bum cast and fail, imo.

Paul

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