Hey Matt,
thanks for the suggestion! I like the idea of having those numbers encapsulated
in some sort of data structure. But I don't know if an enum fits the purpose.
Maybe I got you wrong. Can you give a code snippet? Defining an enum for float
values would require to implement a private float field on that enum and a
constructor. For example:
private static enum TransformatioCosts {
WRAPPER(0.25f),
INTERFACE(0.25f),
SUPERCLASS(1.0f),
NON_FOUND(1.5f);
private final float value;
TransformationCosts(float value){
this.value = value;
}
}
Reading out the values would look like:
[...]
costs += TransformationCosts.WRAPPER.value;
[...]
I would rather go for an Interface that defines the numbers as constants:
private interface TransformationCosts {
public static final WRAPPER = 0.25f;
public static final INTERFACE = 0.25f;
public static final SUPERCLASS = 1.0f;
public static final NON_FOUND = 1.5f;
}
where the call would look like:
[...]
costs += TransformationCosts.WRAPPER;
[...]
What do you think?
Regards
Benedikt
----- Original Message -----
From: gudnabr...@gmail.com
To: dev@commons.apache.org
Date: 30.01.2012 23:42:06
Subject: Re: [SANDBOX][BeanUtils2] About magic numbers in
AccessibleObjectsRegistry.MethodsRegistry.getObjectTransformationCost(Class
srcClass, Class destClass)...
> If we're just talking about a nice way to deal with these magic
> numbers perhaps an enumeration would be a nice way to couple each
> number with a mnemonic description of its intended use? Thus multiple
> enum members could return the weight 0.25f, for example.
>
> Matt
>
> On Mon, Jan 30, 2012 at 4:40 PM, Matt Benson <gudnabr...@gmail.com> wrote:
>> On Mon, Jan 30, 2012 at 4:36 PM, Benedikt Ritter
>> <b...@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
>>>> <b...@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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