2017-11-13 22:30 GMT+01:00 Nicolas Cellier <
nicolas.cellier.aka.nice at gmail.com>:

>
>
> 2017-11-13 22:29 GMT+01:00 Nicolas Cellier <nicolas.cellier.aka.nice@
> gmail.com>:
>
>>
>>
>> 2017-11-13 22:25 GMT+01:00 <commits at source.squeak.org>:
>>
>>> Nicolas Cellier uploaded a new version of Kernel to project The Inbox:
>>> http://source.squeak.org/inbox/Kernel-nice.1120.mcz
>>>
>>> ==================== Summary ====================
>>>
>>> Name: Kernel-nice.1120
>>> Author: nice
>>> Time: 13 November 2017, 10:24:19.857289 pm
>>> UUID: 24277641-be23-40ea-85ef-1db0d48f63d3
>>> Ancestors: Kernel-mt.1119
>>>
>>> 1) Use // in Fraction>>gcd:, rather than / will was invoking the same
>>> gcd: computation 4 times!
>>>
>> argh, "which was invoking", I did not finish to rephrase :(
>>
>> 2) Enhance the Fraction comment
>>>
>> This is in inbox because a class comment is something difficult to make
>> right and will benefit peer advices.
>>
> benefit from, but it seems my hands are a bit decoupled from my brain this
> evening...
>
>> Feel free to improve!
>>
>>
>>> The Fraction comment SHALL tell about the expected class invariants.
>>> At least, it should help answering questions like:
>>>
>>> https://stackoverflow.com/questions/46942103/squeak-smalltal
>>> k-why-sometimes-the-reduced-method-doesnt-work
>>>
>>> https://stackoverflow.com/questions/46905203/squeak-smalltal
>>> k-why-reduction-of-a-fraction-does-not-happen-after-numerator-an
>>>
>>> While at it, also tell why 3 isFraction answers true, and 3.0 asFraction
>>> -> an Integer, not a Fraction.
>>> VW (st80?) has chosen better #isRational and #asRational messages for
>>> making things a bit more clear, but without a Rational superclass, it's not
>>> that obvious...
>>>
>>> =============== Diff against Kernel-mt.1119 ===============
>>>
>>> Item was changed:
>>>   Number subclass: #Fraction
>>>         instanceVariableNames: 'numerator denominator'
>>>         classVariableNames: ''
>>>         poolDictionaries: ''
>>>         category: 'Kernel-Numbers'!
>>>
>>> + !Fraction commentStamp: 'nice 11/13/2017 22:09' prior: 0!
>>> + Fraction provides methods for dealing with fractions like 1/3 as a
>>> ratio of two integers (as apposed to a decimal representation 0.33333...).
>>> - !Fraction commentStamp: '<historical>' prior: 0!
>>> - Fraction provides methods for dealing with fractions like 1/3 as
>>> fractions (not as 0.33333...).  All public arithmetic operations answer
>>> reduced fractions (see examples).
>>>
>>> + instance variables:
>>> +       numerator       <Integer> the number appearing before the
>>> fraction bar (above)
>>> +       denominator     <Integer> the number appearing after the
>>> fraction bar (below)
>>> +
>>> + A Fraction is generally created by sending the message / to an
>>> Integer, like in
>>> - instance variables: 'numerator denominator '
>>>
>>> +     1 / 3
>>> - Examples: (note the parentheses required to get the right answers in
>>> Smalltalk and Squeak):
>>>
>>> + Alternatively, it is possible to create a new instance of Fraction by
>>> sending #numerator:denominator: to the class.
>>> + In this later case, it is then user responsibility to ensure that it
>>> conforms to the following invariants:
>>> +
>>> + - the denominator shall allways be positive.
>>> +   A negative Fraction shall have a negative numerator, never a
>>> negative denominator.
>>> +   Example: 1 / -3 will return -1/3
>>> + - the denominator shall allways be greater than 1.
>>> +   A Fraction with denominator 1 shall be reduced to its numerator (an
>>> Integer).
>>> +   Example 3 / 1 will answer 3 (the Integer) not 3/1
>>> + - the numerator and denominator shall never have common multiples.
>>> +   Common multiples shall allways be simplified until (numerator gcd:
>>> denominator) = 1.
>>> +   Example 8 / 6 will answer 4 / 3, because both 8=2*4 and 6=2*3 are
>>> both divisible by 2.
>>> +
>>> + A Fraction non conforming to above invariants could be the cause of
>>> undefined behavior and unexpected results.
>>> + If unsure, it is advised to send the message #reduced to the freshly
>>> created instance so as to obtain a conforming Fraction, or an Integer.
>>> +
>>> + Note that Fraction and Integer represent together the set of Rational
>>> numbers:
>>> + - Integer is a subset of rational (those which are whole numbers)
>>> + - Fraction is used for representing the complementary subset of
>>> rational (those which are not whole numbers)
>>> +
>>> + There could have been a Rational superclass to both Integer and
>>> Fraction, and a message #isRational for testing if a Number is a Rational,
>>> as well as a message #asRational for converting a Number to a Rational.
>>> + But this level of indirection is not strictly necessary: instead, the
>>> notion of Rational and Fraction are collapsed in Squeak, and Integer are
>>> considered as a sort of special Fraction with unitary denominator.
>>> + Thus #isFraction is the testing message, to which every Integer will
>>> answer true, since considered as a sort of Fraction.
>>> + And #asFraction is the conversion message, that may answer an instance
>>> of Fraction of Integer, depending if the corresponding rational number is
>>> whole or not.
>>> +
>>>
>>
of Fraction OR Integer...

+ All public arithmetic operations will answer reduced fractions.
>>> + Examples:
>>> +
>>>   (2/3) + (2/3)
>>> + (2/3) + (1/2)         "case showing reduction to common denominator"
>>> + (2/3) + (4/3)         "case where result is reduced to an Integer"
>>> + (2/3) raisedToInteger: 5               "fractions also can be
>>> exponentiated"
>>> - (2/3) + (1/2)          "answers shows the reduced fraction"
>>> - (2/3) raisedToInteger: 5               "fractions also can have
>>> exponents"
>>>   !
>>>
>>> Item was changed:
>>>   ----- Method: Fraction>>gcd: (in category 'arithmetic') -----
>>>   gcd: aFraction
>>>         | d |
>>>         d := denominator gcd: aFraction denominator.
>>> +       ^(numerator *(aFraction denominator//d) gcd: aFraction
>>> numerator*(denominator//d)) / (denominator//d*aFraction denominator)!
>>> -       ^(numerator *(aFraction denominator/d) gcd: aFraction
>>> numerator*(denominator/d)) / (denominator/d*aFraction denominator)!
>>>
>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.squeakfoundation.org/pipermail/squeak-dev/attachments/20171113/93177ad6/attachment.html>