Nope, not a bug. If you use Float, then you have to know that (x -y) isZero and (x = y) are two different things. Example; Float infinity In your case you want to protect against (x-y) isZero, so just do that. 2017-11-09 15:15 GMT+01:00 Tudor Girba <tudor@tudorgirba.com>:
Hi,
I just stumbled across this bug related to the equality between fraction and float: https://pharo.fogbugz.com/f/cases/20488/x-y-iff-x-y-0-is- not-preserved-in-Pharo
In essence, the problem can be seen that by doing this, you get a ZeroDivide: x := 0.1. y := (1/10). x = y ifFalse: [ 1 / (x - y) ]
The issue seems to come from the Float being turned to a Fraction, rather than the Fraction being turned into a Float:
Fraction(Number)>>adaptToFloat: rcvr andCompare: selector "If I am involved in comparison with a Float, convert rcvr to a Fraction. This way, no bit is lost and comparison is exact."
rcvr isFinite ifFalse: [ selector == #= ifTrue: [^false]. selector == #~= ifTrue: [^true]. rcvr isNaN ifTrue: [^ false]. (selector = #< or: [selector = #'<=']) ifTrue: [^ rcvr positive not]. (selector = #> or: [selector = #'>=']) ifTrue: [^ rcvr positive]. ^self error: 'unknow comparison selector'].
^ *rcvr asTrueFraction perform: selector with: self*
Even if the comment says that the comparison is exact, to me this is a bug because it seems to fail doing that. What do you think?
Cheers, Doru
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