September 2020 - Pharo-users

Can it do this way ?
by Roelof Wobben Sept. 2, 2020

Sept. 2, 2020

Hello, I have now a challenge where I have to validate a ISBN number. Can I do something like this on the class side : (string isEmpty) Â Â ifTrrue: [ ^ false] Â ifFalse:Â [ digits:= something. Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â controlDigit := something. Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â self validateISBNNumber] where on the validateISBNNumber I use the instance variables digits and controlDigit to validate the ISBN number on the instance side. Roelof

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Re: [Pharo-users] mentoring contined I hope
by Richard O'Keefe Sept. 2, 2020

Sept. 2, 2020

Richard Sargent is giving good advice that you cannot use in Exercism. Your code MUST pass the exercism tests and that means it MUST NOT limit the hour or minute ranges. On Tue, 1 Sep 2020 at 08:58, Roelof Wobben via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > > I would argue against that approach. Make it a requirement that a given > API must be used with correct values. > e.g. #hours:minutes: requires hours between 00 and 23 and minutes between > 00 and 59. > > If you want to convert equivalent time values, use a specific API. For > example, many time implementations publicly define a seconds-based API, > such as Time class>>#fromSeconds:. You can do the same with your > implementation with a class-side #fromMinutes: method. (The corresponding > instance methods would be #asSeconds and #asMinutes or something similar.) > > > > Moment, I do not know if I understand you right. > > so I would use the given method and use on the instance another function > that takes care of the converting to or a valid time object or for example > convert it to minutes and on display take care that a valid time is shown. > > Do I understand you right ? > > I send this personal because I cannot send to the mailing list according > to some spam list >

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Re: [Pharo-users] mentoring continued I hope
by Richard Sargent Sept. 2, 2020

Sept. 2, 2020

On Sun, Aug 30, 2020 at 10:04 PM Roelof Wobben via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > Hello, > > I have this challenge from exercism : > https://github.com/exercism/pharo-smalltalk/tree/master/exercises/clock > > and this function is given : > > hour: anInteger minute: anInteger2 > self shouldBeImplemented > > > Schould I make it on this class method work that the minutes will not > exceed the 59 minutes > So when for example when 70 min are given so hour:0 minute:70 it will > be converted to hour: 1 minutes: 10 > I would argue against that approach. Make it a requirement that a given API must be used with correct values. e.g. #hours:minutes: requires hours between 00 and 23 and minutes between 00 and 59. If you want to convert equivalent time values, use a specific API. For example, many time implementations publicly define a seconds-based API, such as Time class>>#fromSeconds:. You can do the same with your implementation with a class-side #fromMinutes: method. (The corresponding instance methods would be #asSeconds and #asMinutes or something similar.) or can I better do this on the instance side. > > Regards, > > Roelof > > >

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Re: [Pharo-users] mentoring continued I hope
by Richard O'Keefe Sept. 2, 2020

Sept. 2, 2020

I have always found it annoying that the exercism specifications do not spell things out, so you HAVE to read the tests to find out what you are supposed to do, which pretty much spoils the point of them BEING tests. In this case, we note that there is a test case where the number of hours is 100, and it is to be accepted as meaning '04'. There is also a test case where the number of minutes is 160 and it is to be taken as 40 minutes plus 2 hours. So the only way you can pass the tests is something like class methods for: 'instance creation' hours: h minutes: m ^self new setMinutesSinceMidnight: (h * 60 + m bitOr: 0) \\ 1440 methods for: 'private' setMinutesSinceMidnight: m minutesSinceMidnight := m. methods for: 'accessing' hour ^minutesSinceMidnight // 60 minute ^minutesSinceMidnight \\ 60 The only *checking* that is involved is that the hour and minute counts must be integers, which I used " bitOr: 0" to do. What's the best way to do thisE? As for where to do checking in general, put it as close to the encapsulation boundary as you reasonably can. If there is a PUBLIC method for changing the time on a Clock, you need to put the checking in that method. If (as here) a clock value is supposed to be immutable, put it in the instance creation method. On Mon, 31 Aug 2020 at 18:18, Roelof Wobben via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > Hello, > > I have this challenge from exercism : > https://github.com/exercism/pharo-smalltalk/tree/master/exercises/clock > > and this function is given : > > hour: anInteger minute: anInteger2 > self shouldBeImplemented > > > Schould I make it on this class method work that the minutes will not > exceed the 59 minutes > So when for example when 70 min are given so hour:0 minute:70 it will > be converted to hour: 1 minutes: 10 > or can I better do this on the instance side. > > Regards, > > Roelof > > >

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Re: mentoring contined I hope
by Roelof Wobben Sept. 1, 2020

Sept. 1, 2020

Op 1-9-2020 om 21:11 schreef Richard Sargent: > You will discover an error when you write your tests, but that's fine. > It's why you write tests. :-) > > #validateTime:minute: is a poor name choice for a few reasons. > - there is no validation going on. Validation would report an error > for invalid data. > - there is nothing to suggest what the first argument is, the > counterpart to "minute:". > - it doesn't suggest there will be a new Time ("Clock") created. > - it's a "verb phrase" saying it will *do* something rather than > answer something (I'm being vague here. Sorry.) > > I suggest #normalizedForHour:minute:. > It explains that it will normalize the values and that it will answer > a normalized result (it still isn't great, as it doesn't explain what). > Perhaps better would be #newNormalizedForHour:minute:. > > Thanks, I think I found the error and solved it hour: anInteger minute: anInteger2 Â Â Â ^ self new Â Â Â Â Â Â hour: (anInteger2 // 60 + anInteger) % 24; Â Â Â Â Â Â minute: anInteger2 % 60; Â Â Â Â Â Â yourself instance side : printOn: aStream Â Â Â ^ aStream Â Â Â Â Â Â nextPutAll: self hour asTwoCharacterString; Â Â Â Â Â Â nextPut: $:; Â Â Â Â Â Â nextPutAll: self minute asTwoCharacterString and the tests are green now time to sleep and tomorrow time to figure out how to add and substract minutes. As I remember it right you gave already the answer to me somewhere in our conversation Roelof I

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Re: mentoring contined I hope
by Roelof Wobben Sept. 1, 2020

Sept. 1, 2020

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Re: mentoring contined I hope
by Roelof Wobben Sept. 1, 2020

Sept. 1, 2020

2 1