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From Matt Benson <gudnabr...@gmail.com>
Subject Re: [SANDBOX][BeanUtils2] About magic numbers in AccessibleObjectsRegistry.MethodsRegistry.getObjectTransformationCost(Class srcClass, Class destClass)...
Date Mon, 30 Jan 2012 22:40:24 GMT
On Mon, Jan 30, 2012 at 4:36 PM, Benedikt Ritter
<bene@systemoutprintln.de> wrote:
> Am 30.01.2012 23:21, schrieb Matt Benson:
>
>> Guys, if I know which magic numbers you are discussing, I believe they
>> are intended to allow a "weight" to be assigned to the action of
>> calling a given method(or constructor) with a given set of parameters:
>>  the smaller the weight, the more directly assignable the parameters
>> are to the method being tested.  We can thus determine, among several
>> potential matching signatures, which matches the most closely and
>> therefore which we expect the compiler would have decided was meant by
>> an equivalent call made from actual source code.  My apologies if I've
>> completely missed the point of the discussion as I've only been
>> following loosely.
>
>
> Hey Matt,
>
> that's exactly what we were talking about! Thank you very much. Do you know
> where the penalties that make up the "weights" come from?

I don't know exactly.  I would imagine that they were just made up as
a set of numbers that would behave in the way the original contributor
wanted.  Perusing the JLS might bear fruit (but then again it might
not).  :)

Matt

> Looking at
> BeanUtils1 MethodUtils.getObjectTransformationCost() I can see that:
> * having to wrap a primitive costs 0.25f
> * having an interface match costs 0.25f
> * having to go one step higher in the class hierarchy costs 1.0f
> * having no match in the complete hierarchy costs 1.5f
> Are those values extracted from the java spec/the java compiler itself?
> Having that information documented in the code would be off great value, if
> for what ever reason the implementation has to change some day.
>
> good night,
> Benedikt
>
>
>>
>> HTH,
>> Matt
>>
>> On Mon, Jan 30, 2012 at 4:14 PM, Benedikt Ritter
>> <bene@systemoutprintln.de>  wrote:
>>>
>>> Am 30.01.2012 20:50, schrieb Simone Tripodi:
>>>
>>>>> Sadly nothing is mentioned about the said magic numbers. So we are at
>>>>> the
>>>>> start again. Any ideas, how to handle this issue? :)
>>>>
>>>>
>>>>
>>>> which issue? is there any weird behavior introduced by the procedure?
>>>>
>>>
>>> No, everything seems to work properly. But I don't understand it and that
>>> bugs me ;-)
>>>
>>>
>>>> anyway, we don't have any chance to understand where/how they come
>>>> from, so just extract them as constants, it that has worked from '04
>>>> will continue doing it, unless a bug surprisingly comes up.
>>>>
>>>
>>> okay, you will see a patch for that sometime in the next days.
>>>
>>> buona notte,
>>> Benedikt
>>>
>>>
>>>> TIA,
>>>> -Simo
>>>>
>>>> http://people.apache.org/~simonetripodi/
>>>> http://simonetripodi.livejournal.com/
>>>> http://twitter.com/simonetripodi
>>>> http://www.99soft.org/
>>>>
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>>>
>>>
>>>
>>>
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>>
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>
>
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