[squeak-dev] Float parsed as a Fraction bug
J. Vuletich (mail lists)
juanlists at jvuletich.org
Thu Aug 7 16:40:55 UTC 2014
Hi Folks,
Just tried Smalltalk-80 (actually Apple Smalltalk-80 running in Mini vMac).
1e-3 "printIt" (1/1000)
1e-3 class "printIt" Fraction
1e3 "printIt" 1000
1e3 class "printIt" SmallInteger
This has always been the behavior in Squeak too.
Also check these comments from Dan:
http://lists.squeakfoundation.org/pipermail/squeak-dev/2000-March/013368.html
I don't think this is a bug at all.
BTW, Cuis also supports 1r111111111111 = 12 after this :)
Cheers,
Juan Vuletich
Quoting Eliot Miranda <eliot.miranda at gmail.com>:
> On Thu, Aug 7, 2014 at 9:05 AM, Levente Uzonyi <leves at elte.hu> wrote:
>
>> On Wed, 6 Aug 2014, Eliot Miranda wrote:
>>
>>> Hi Levente,
>>>
>>> On Wed, Aug 6, 2014 at 11:43 AM, Levente Uzonyi <leves at elte.hu> wrote:
>>> On Wed, 6 Aug 2014, Eliot Miranda wrote:
>>>
>>> Hi All,
>>> Squeak trunk also suffers from the Float parsed
as a
>>> Fraction bug:
>>>
>>> 1e-8 class Fraction
>>> 1.0e8 class Float
>>>
>>> I'm not entirely sure about it being a bug. I've checked Squeak 3.8
>>> (pre-SqNumberParser), and it also parsed that literal as a Fraction.
>>> If I want a Float, I can be explicit and use 1.0e-8.
>>>
>>> IMO it very much *is* a bug. Smalltalk-80 has never supported
>>> Fraction literals. They're always written as division expressions.
>>> Fraction answers false to isLiteral. Just because it worked that
way
>>> doesn't mean it was right. I suspect no one noticed. Allowing
>>> Fraction literals feels like a big change to me.
>>
>> It's more like undefined behavior than a bug IMHO, though the lack of
>> #isLiteral makes me think that the Fractions are not intentional.
>> Interesting how Nicolas's SqNumberParser behaves the same way as the
>> previous number parser in this case.
>>
>>> I made a modified version of Fraction >> #printOn:base: which
>>> outputs the literal format if possible. The change "fixes" the
>>> debugger (note that itw was way less broken in Squeak than in Pharo
>>> anyway).
>>> The only drawback I found is that some fractions become a bit
>>> more "complex" when printed, e.g. 3/4 => 75e-2
>>>
>>> OK, but is this the right fix? What does everybody think? Keep the
>>> language unchanged or add Fraction literals and add another
>>> incompatibility with other dialects?
>>
>> I don't think that anyone ever used this "feature" before, so doing
>> what other dialects do is probably the best way to resolve this.
>
>
> Agreed. Smalltalk-80 v2 had no literal fractions. ObjectWorks
and
> VisualWorks have never had literal fractions. I can't speak for other
> dialects, but I'm fairly sure none of the Smalltalk/V, Team/V lineage
> had literal Fractions either.
>
>
>>> If Fractions are literals
>>> - what is the semantics of 1/0 (easy, it is not a literal, but needs
>>> to be stated)?
>>> - what is [1/0.1] on: ZeroDivide do: [:ex| #error] ? Is it 10.0 or
>>> #error, i.e. is 1/0.1 10.0 or 1 / 0 followed by the Integer 1?
>>
>> I did not propose to make all fractions literals. My implementation
>> simply prints decimal fractions with the exponent notation, e.g. 3/4 is
>> printed as 75-e2, but 2/3 is still printed as (2/3).
>>
>> Levente
>>
>>>
>>> Levente
>>> --
>>> eek! Eliot
>>>
>>> --
>>> best,Eliot
>>>
>>
>>
>
>
> --
> best, Eliot
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