On Wed, May 30, 2012 at 2:37 PM, Henrik Sperre Johansen <
[email protected]> wrote:
> On 30.05.2012 14:05, Mariano Martinez Peck wrote:
>
>> Hi guys. I found a problem while working with FuelPreview where we store
>> objects of the graph in a Set. While doing a collect, there was an error
>> because an implementation of #= was assuming that the argument was of a
>> certain shape. Of course, that should answer false instead. So I wrote this
>> test to see all existing wrong implementations:
>>
>> testAllClassesImplementSafeEqu**alsMethod
>> "This tests that all classes in the system that implements #= do it in a
>> way that they don't throw error when passing as an argument something
>> different from expected. The correct behavior is that #= answers false."
>> | wrongClasses |
>> wrongClasses := IdentityDictionary new.
>> ((SystemNavigation default allImplementorsOf: #=)
>> collect: [:each | each methodClass])
>> do: [:each |
>> | instance |
>> "Some classes like CompiledMethod override basicNew to
>> throw an error.
>> In any case, the comparison will be false, so no problem"
>> [instance := each basicNew] on: Error do: [].
>> [instance = Object new]
>> on: Error
>> do: [: err | wrongClasses at: each put: err ]].
>> self assert: wrongClasses isEmpty
>>
>>
>> The result is: {Magnitude. WideCharacterSet. KMKeymap. MCMockDefinition.
>> ScaledDecimal. MCSnapshot}
>>
>> So, my I think we should change #= in those classes by adding:
>>
>> self == aKeymap
>> ifTrue: [ ^ true ].
>> self class = aKeymap class
>> ifFalse: [ ^ false ].
>>
>> at the beginning of the #=
>>
>> what do you think? if agree, I open an issue.
>>
>>
>> --
>> Mariano
>> http://marianopeck.wordpress.**com <http://marianopeck.wordpress.com>
>>
>> I'd test against self species rather than self class, since it gives
> greater flexibility for user-defined instances to potentially = classes in
> the system.
>
> In other word, #class has a very strict meaning which would hinder
> extensibility, #species less so.
>
>
Ok, I see. But the classes are only a few (five). So you recommend you use
self species instead of self class even if we "analyze" those 5 classes to
see if it is worth it or not (for example, we check if they do override
#species or not) ?
and btw...the automatic #hash and #= generator, shouldn't use #species
rather then #classes to?
thanks
> Otherwise I agree.
>
> Cheers,
> Henry
>
>
--
Mariano
http://marianopeck.wordpress.com
