Re: [picocontainer-dev] ConfigParameterTestCase / ConfigParameter

Paul Hammant wrote:

> Jörg,
> 
> 
>>
>> [snip]
>>
>> so we would have instead:
>>
>> private static final Map<Class, ParameterFactory>
>>   stringConverters = new HashMap<Class, ParameterFactory>();
>> static {
>>     stringConverters.put(Integer.class,
>>         new ValueOfParameterFactory<Integer>();
>>     stringConverters.put(Double.class,
>>         new ValueOfParameterFactory<Double>();
>>     stringConverters.put(Boolean.class,
>>         new ValueOfParameterFactory<Boolean>();
>>     stringConverters.put(Long.class,
>>         new ValueOfParameterFactory<Long>();
>>     stringConverters.put(File.class,
>>         new StringConstructorParameterFactory<File>();
>>     ...
>> }
>>
>> We might find better names for the classes though. We may collect
>> them in an
>> own package.
> 
> I appreciate we can reduce the (inner) class count with this design,
> but we'd be relying on reflection, as Sun did not see fit to have an
> interface for this boiler-plate stuff (valueOf).
>
> I'm not sure its worth the cost.
> 
>>
>>> I think for now, a fixed list of conversions is fine - going up to
>>> the set that XStream caters for.
>>
>> You can only use the SingleValueConverters anyway and with the
>> generified
>> versions from my last posting, you can handle quite a lot.
>>
> 
> Explain a bit more? As I see it ....
> 
>     class ValueOfParameterFactory<T> extends APF<T> {
>         T fromString(String s) {
>             return T.valueOf(s);
>         }
>     }
> 
> .... can't work because valueOf is not part of an interface/
> abstraction that safe for generics.  You'd have to do that fragment
> with reflection ... making it uglier and slower.

Seems I have to learn a lot more about Java generics, I did not expect to
have here reflection involded at all. C++ templates were a wonderful
mechanism ;-)

- Jörg


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