And I just checked, and:

1) the senders of isFraction would work equally well if
Integer>>isFraction did answer true.
  This is because they only expect the fraction to answer to
#numerator and #denominator, and Integer does that quite well
2) this would fast up mixed Integer/Fraction arithmetic.

3) the senders of asFraction that really expect a Fraction are
* Fraction>>adaptToInteger: rcvr andSend: selector
* Integer>>adaptToFraction: rcvr andSend: selector
But the later would be useless if Integer>>isFraction did answer true.
4) the other senders of #asFraction are in ScaledDecimal and don't
care whether the Fraction really is a Fraction or an Integer

So it might be time to enforce this peculiarity:
Integer>>isFraction
    "Answer true because every Integer is polymorphic with a Fraction."
Integer>>asFraction
    "See Integer>>#isFraction."
    ^self

Nicolas

2011/9/7 Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com>:
> OK, I had a chance to open an image and I see I'm responsible for this problem.
> Levente changed the printing method, I recognized an already existing
> Fraction>>printTruncatedOn:showingDecimalPlaces: and decided to use
> it. But this message is not Integer friendly indeed.
>
> Otherwise, there is no problem if the fraction ivar is an Integer, it
> alerady was before, and can continue to be, as long as Integer
> instances are polymorphic to Fraction (what they mostly are).
> I gonna correct the mess this evening, thanks for reporting!
>
> Nicolas
>
>
> 2011/9/7 Frank Shearar <frank.shearar at gmail.com>:
>> On 7 September 2011 12:32, Nicolas Cellier
>> <nicolas.cellier.aka.nice at gmail.com> wrote:
>>> Isn't it also the case with (ScaledDecimal newFromNumber: 1.0 scale: 0) ?
>>
>> It's true for any integral-valued float. Somewhere near the bottom of
>> Float >> #asTrueFraction the line
>>
>>  result := signedFraction bitShift: zeroBitsCount negated
>>
>> returns an Integer.
>>
>> Presumably (and I'm really just guessing here), we could say
>>
>>    result := Fraction
>>        numerator: (signedFraction bitShift: zeroBitsCount negated)
>>        denominator: 1
>>
>> frank
>>
>>> 2011/9/7 Frank Shearar <frank.shearar at gmail.com>:
>>>> Evaluate the following:
>>>>
>>>> 0s0 "=> 0s0"
>>>> ScaledDecimal newFromNumber: 0 scale: 0 "=> 0s0"
>>>>
>>>> 0.0s0 "=> 0s0"
>>>> ScaledDecimal newFromNumber: 0.0 scale: 0 "=> MNU: SmallInteger
>>>> doesn't understand printTruncatedOn:showingDecimalPlaces:"
>>>>
>>>> The MNU happens because in ScaledDecimal class >> #newFromNumber:scale: we say
>>>>
>>>>    "..." aNumber asFraction "..."
>>>>
>>>> and when aNumber = 0.0, aNumber asFraction = 0, which is a
>>>> SmallInteger and not a Fraction.
>>>>
>>>> (Recorded as http://bugs.squeak.org/view.php?id=7667)
>>>>
>>>> frank
>>>>
>>>>
>>>
>>>
>>
>>
>