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:
testAllClassesImplementSafeEqualsMethod
"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
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.
Otherwise I agree.
Cheers,
Henry
