Status: Accepted
Owner: marianopeck
Labels: Type-Bug
New issue 5997 by marianopeck: Classes that implement unsafe equals
http://code.google.com/p/pharo/issues/detail?id=5997Hi 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 new] 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 == anObject
ifTrue: [ ^ true ].
self species = anObject species
ifFalse: [ ^ false ].
at the beginning of the #=
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