Ooops I wasn't int the mailing list, lets try again
Hello Steph,
I have questions about the concept because,probably, I miss something.
I am not sneaky, let me explain.
If we analyse the Kernel Numbers package, and we dissect the relation
between Float, Fraction and Integer (Pharo 5.0) for example, the '+' method
in the class Integer. We read:
+ aNumber
"Refer to the comment in Number + "
aNumber isInteger
ifTrue: [ self negative == aNumber negative
ifTrue: [ ^ (self digitAdd: aNumber)
normalize ]
ifFalse: [ ^ self digitSubtract: aNumber ]
].
aNumber isFraction
ifTrue: [ ^ Fraction
numerator: self * aNumber denominator +
aNumber numerator
denominator: aNumber denominator ].
^ aNumber adaptToInteger: self andSend: #+
and we have similar '+'method containing complementary tests in the other
class Float and Fraction.
And an overall '+' method in the class Number
+ aNumber
"Answer the sum of the receiver and aNumber."
self subclassResponsibility
I precise that a long time ago as an academic exercice, I developped a
'Complex' class using this way above (So I add tests).
My questions:
You say it's better to use double dispatch, so in this case, can we apply it
for the Number subclasses?
It is good or unnecesary to create a super class 'Dicable' containing a '+'
method with
+ aNumber
"Answer the sum of the receiver and aNumber."
self subclassResponsibility
? is it wasted time or safe code?
Yves
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