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Re: [Pharo-users] how to model this a better way

by Ben Coman

On Fri, 19 Apr 2019 at 01:33, Roelof Wobben <r.wobben(a)home.nl> wrote: > > oke > > Maybe I understand something not right, > > Lets say we have this scenario. > > Robot is on position (0,0) > now it turns left so the robot faces East I think the required method was mentioned previously, but here is how to discover it yourself... + Tool > Finder > Examples + Enter... (0@1) . (1@0) <Search> finds... Point>>leftRotated e.g. (0@1) leftRotated ==> (1@0) On Fri, 19 Apr 2019 at 01:39, Roelof Wobben <r.wobben(a)home.nl> wrote: > > Ben, > > I have such a dictionary in my first attempt to solve this one. > and another one for the facing. This sounds strange that you have two Dictionaries. It can be useful to encapsulate the mapping to avoid that being littered around your Robot code... Object subclass: #Facing instanceVariables: 'map directionVector' Facing >> initialize map := Dictionary newFromPairs: { 'north'. (0@1) . 'west' . (0@1) leftRotated . 'south'. (0@1) leftRotated leftRotated. 'east' . (0@1) rightRotated }. directionVector := map atRandom. Facing >> directionString ^ map keyAtValue: directionVector Facing >> printOn: aStream " Facing new inspect " aStream nextPutAll: self className, '-', self directionString "The above is produces a minimum-viable object that displays nicely in Inspector to facilitate incrementally coding your scenario in TDD way..." > Lets say we have this scenario: TestCase subclass: FacingTest FacingTest>>testAllTogether |position facing| "Robot begins at (0,0) facing north" position := 0@0. facing := Facing new face: 'north'. self assert: facing printString equals: 'Facing-north'. "then it turns right so it faces >>EAST<<" facing turnRight. self assert: facing printString equals: 'Facing-east'. "then it moves one step so the new position is (-1,0)" position := position + (facing movementSteps: 1). self assert: position equals: (-1@0). "then it turns left so it faces north again" facing turnLeft. self assert: facing printString equals: 'Facing-north'. "then it moves one step so the new position is (-1,1)" position := position + (facing movementSteps: 1). self assert: position equals: (-1@1). Which I'll leave as an exercise for you to complete with these hints... Facing >> face: aDirectionString directionVector := ... Facing >> turnRight directionVector := ... Facing >> turnLeft directionVector := ... Facing >> movementSteps: steps ^ ... > so if I see it , the position has nothing to do with the direction the > robot is facing yes. they only interact when the robot moves > this [position] is only important for finding out a new direction no - position has no impact for determining the new direction > or to find out if the x or the y needs to change. You don't need to treat x and y separately. Using Points for both the "position" and "directionVector" facilitates simple addition. cheers -ben > > Roelof > > > > Op 18-4-2019 om 19:17 schreef Richard Sargent: > > On Thu, Apr 18, 2019 at 10:01 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >> >> yep, I have read that one >> but I never gets a answer how I can "convert" a point to something like north, east >> >> because the challenge wants this to be the answer : >> >> (Dictionary new >> add: 'direction' -> 'north'; >> add: >> 'position' >> -> >> (Dictionary new >> add: 'x' -> 0; >> add: 'y' -> 0; >> yourself); >> yourself) > > > If you have previously defined a "representation map", you would be golden. > > e.g. > Dictionary new > at: self northDirectionVector put: 'north'; > at: self eastDirectionVector put: 'east'; > at: self southDirectionVector put: 'south'; > at: self westDirectionVector put: 'west'; > yourself. > > Then: > (Dictionary new > add: 'direction' -> (self directionRepresentationMap at: self directionVector); > ... > >> >> >> and I think I need then to use if then , which I try to avoid as much as possible. >> >> Roelof >> >> >> >> Op 18-4-2019 om 18:33 schreef Richard Sargent: >> >> On Thu, Apr 18, 2019 at 8:57 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >>> >>> Hello, >>> >>> I know I have asked earlier but im still stuck on this one : https://github.com/exercism/problem-specifications/blob/master/exercises/ro… >>> >>> I tried with all double dispatch but that will be a lot of duplicate classes >>> >>> The problem I cannot solve right is that a robot can move or turn. when a robot turns only the direction the robot is facing changes and the position not. when a robot moves the facing direction stays the same but the position changes. but the change is dependend on the facing. Also the new facing direction is dependend on the old facing direction/ >>> How can I model this the best. >>> >>> I already have a object Robot that contains the facing direction and the current position >>> or tried without it but then I use a lot of if then's >>> >>> >>> so it there a better way to model this problem so it will be all nice and readable code. >> >> >> If I remember correctly, Richard O'Keefe gave you a viable design. 1) Use a Point for your direction vector. 2) Use a second Point for your position. >> >> e.g. if you align the compass with a Cartesian plane, 0@1 is North, 0@-1 is South, 1@0 is East, and -1@0 is West. When you move, you add the direction vector to your current position. If you allow movements of greater than a single unit, you multiply the direction vector by the distance before adding that product to the position. >> >>> >>> Roelof >>> >> >

April 19, 2019

Re: [Pharo-users] Why are package tags not proper sub-packages?

by Sean P. DeNigris

Ben Coman wrote >> The implication here is that extension methods canât live on the tag >> (they >> live on the parent package Won't that cause existing code not designed with that restriction in mind to be lost on save? ----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

April 19, 2019

Re: [Pharo-users] how to model this a better way

by Tim Mackinnon

You quickly find itâs a more interesting exercise than just a âpoint and dictionaryâ, particularly if you want to do it in an elegant Smalltalk way (but not over do it either). The interesting bit is that when facing a new direction, you need to know how to advance in that direction , and also what âleftâ and ârightâ of that direction are too. So it teases out having some objects and techniques for this. For those interested - join exercism-Pharo (https://exercism.io/tracks/pharo-smalltalk/installation) in non mentor mode and you can easily download it with the tests and try it out yourself (without running through the other exercises). Tim Sent from my iPhone > On 18 Apr 2019, at 21:41, Richard Sargent <richard.sargent(a)gemtalksystems.com> wrote: > > Your system would have instance variables holding the cardinal directions and another holding the current direction vector. > e.g. > north := DirectionVector x: 0 y: 1 name: 'north'. > > Your robot would implement e.g. #faceNorth to assign the "north" direction vector to the current direction vector instance variable. > > > >> On Thu, Apr 18, 2019 at 12:17 PM Roelof Wobben <r.wobben(a)home.nl> wrote: >> oke, and how must I see those classes and elemating the need for a lookup. >> >> it may be explained in pseudo-code. >> >> Roelof >> >> >> >> Op 18-4-2019 om 20:28 schreef Richard Sargent: >>>> On Thu, Apr 18, 2019 at 10:33 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >>>> oke >>>> >>>> Maybe I understand something not right, >>>> >>>> Lets say we have this scenario. >>>> >>>> Robot is on position (0,0) >>>> now it turns left so the robot faces East >>> >>> I don't understand what position has to do with direction nor why that would be a problem. They are two distinct attributes. >>> Point and Dictionary are sufficient classes to model the limited requirements of this exercise. >>> You could model a new class DirectionVector which internalizes the Point used to provide the direction and provides its own name, eliminating the need for a look up of any kind. >>> >>>> >>>> or this scenario >>>> >>>> Robot is on position (0,0) >>>> now it turns right so the robot faces west. >>>> >>>> it looks that dictionary cannot provide this answer. >>>> or do I overlook something >>>> >>>> Roelof >>>> >>>> >>>> >>>> Op 18-4-2019 om 19:17 schreef Richard Sargent: >>>>>> On Thu, Apr 18, 2019 at 10:01 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >>>>>> yep, I have read that one >>>>>> but I never gets a answer how I can "convert" a point to something like north, east >>>>>> >>>>>> because the challenge wants this to be the answer : >>>>>> >>>>>> (Dictionary new >>>>>> add: 'direction' -> 'north'; >>>>>> add: >>>>>> 'position' >>>>>> -> >>>>>> (Dictionary new >>>>>> add: 'x' -> 0; >>>>>> add: 'y' -> 0; >>>>>> yourself); >>>>>> yourself) >>>>> >>>>> If you have previously defined a "representation map", you would be golden. >>>>> >>>>> e.g. >>>>> Dictionary new >>>>> at: self northDirectionVector put: 'north'; >>>>> at: self eastDirectionVector put: 'east'; >>>>> at: self southDirectionVector put: 'south'; >>>>> at: self westDirectionVector put: 'west'; >>>>> yourself. >>>>> >>>>> Then: >>>>> (Dictionary new >>>>> add: 'direction' -> (self directionRepresentationMap at: self directionVector); >>>>> ... >>>>> >>>>>> >>>>>> >>>>>> and I think I need then to use if then , which I try to avoid as much as possible. >>>>>> >>>>>> Roelof >>>>>> >>>>>> >>>>>> >>>>>> Op 18-4-2019 om 18:33 schreef Richard Sargent: >>>>>>>> On Thu, Apr 18, 2019 at 8:57 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >>>>>>>> Hello, >>>>>>>> >>>>>>>> I know I have asked earlier but im still stuck on this one : https://github.com/exercism/problem-specifications/blob/master/exercises/ro… >>>>>>>> >>>>>>>> I tried with all double dispatch but that will be a lot of duplicate classes >>>>>>>> >>>>>>>> The problem I cannot solve right is that a robot can move or turn. when a robot turns only the direction the robot is facing changes and the position not. when a robot moves the facing direction stays the same but the position changes. but the change is dependend on the facing. Also the new facing direction is dependend on the old facing direction/ >>>>>>>> How can I model this the best. >>>>>>>> >>>>>>>> I already have a object Robot that contains the facing direction and the current position >>>>>>>> or tried without it but then I use a lot of if then's >>>>>>>> >>>>>>>> >>>>>>>> so it there a better way to model this problem so it will be all nice and readable code. >>>>>>> >>>>>>> If I remember correctly, Richard O'Keefe gave you a viable design. 1) Use a Point for your direction vector. 2) Use a second Point for your position. >>>>>>> >>>>>>> e.g. if you align the compass with a Cartesian plane, 0@1 is North, 0@-1 is South, 1@0 is East, and -1@0 is West. When you move, you add the direction vector to your current position. If you allow movements of greater than a single unit, you multiply the direction vector by the distance before adding that product to the position. >>>>>>> >>>>>>>> >>>>>>>> Roelof >>>>>>>> >>>>>> >>>> >>

April 18, 2019

Re: [Pharo-users] how to model this a better way

by Richard Sargent

Your system would have instance variables holding the cardinal directions and another holding the current direction vector. e.g. north := DirectionVector x: 0 y: 1 name: 'north'. Your robot would implement e.g. #faceNorth to assign the "north" direction vector to the current direction vector instance variable. On Thu, Apr 18, 2019 at 12:17 PM Roelof Wobben <r.wobben(a)home.nl> wrote: > oke, and how must I see those classes and elemating the need for a lookup. > > it may be explained in pseudo-code. > > Roelof > > > > Op 18-4-2019 om 20:28 schreef Richard Sargent: > > On Thu, Apr 18, 2019 at 10:33 AM Roelof Wobben <r.wobben(a)home.nl> wrote: > >> oke >> >> Maybe I understand something not right, >> >> Lets say we have this scenario. >> >> Robot is on position (0,0) >> now it turns left so the robot faces East >> > > I don't understand what position has to do with direction nor why that > would be a problem. They are two distinct attributes. > Point and Dictionary are sufficient classes to model the limited > requirements of this exercise. > You could model a new class DirectionVector which internalizes the Point > used to provide the direction and provides its own name, eliminating the > need for a look up of any kind. > > >> or this scenario >> >> Robot is on position (0,0) >> now it turns right so the robot faces west. >> >> it looks that dictionary cannot provide this answer. >> or do I overlook something >> >> Roelof >> >> >> >> Op 18-4-2019 om 19:17 schreef Richard Sargent: >> >> On Thu, Apr 18, 2019 at 10:01 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >> >>> yep, I have read that one >>> but I never gets a answer how I can "convert" a point to something like >>> north, east >>> >>> because the challenge wants this to be the answer : >>> >>> (Dictionary new >>> add: 'direction' -> 'north'; >>> add: >>> 'position' >>> -> >>> (Dictionary new >>> add: 'x' -> 0; >>> add: 'y' -> 0; >>> yourself); >>> yourself) >>> >> >> If you have previously defined a "representation map", you would be >> golden. >> >> e.g. >> Dictionary new >> at: self northDirectionVector put: 'north'; >> at: self eastDirectionVector put: 'east'; >> at: self southDirectionVector put: 'south'; >> at: self westDirectionVector put: 'west'; >> yourself. >> >> Then: >> (Dictionary new >> add: 'direction' -> (self directionRepresentationMap at: >> self directionVector); >> ... >> >> >>> >>> and I think I need then to use if then , which I try to avoid as much as >>> possible. >>> >>> Roelof >>> >>> >>> >>> Op 18-4-2019 om 18:33 schreef Richard Sargent: >>> >>> On Thu, Apr 18, 2019 at 8:57 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >>> >>>> Hello, >>>> >>>> I know I have asked earlier but im still stuck on this one : >>>> https://github.com/exercism/problem-specifications/blob/master/exercises/ro… >>>> >>>> I tried with all double dispatch but that will be a lot of duplicate >>>> classes >>>> >>>> The problem I cannot solve right is that a robot can move or turn. when >>>> a robot turns only the direction the robot is facing changes and the >>>> position not. when a robot moves the facing direction stays the same but >>>> the position changes. but the change is dependend on the facing. Also the >>>> new facing direction is dependend on the old facing direction/ >>>> How can I model this the best. >>>> >>>> I already have a object Robot that contains the facing direction and >>>> the current position >>>> or tried without it but then I use a lot of if then's >>>> >>>> >>>> so it there a better way to model this problem so it will be all nice >>>> and readable code. >>>> >>> >>> If I remember correctly, Richard O'Keefe gave you a viable design. 1) >>> Use a Point for your direction vector. 2) Use a second Point for your >>> position. >>> >>> e.g. if you align the compass with a Cartesian plane, 0@1 is North, 0@-1 >>> is South, 1@0 is East, and -1@0 is West. When you move, you add the >>> direction vector to your current position. If you allow movements of >>> greater than a single unit, you multiply the direction vector by the >>> distance before adding that product to the position. >>> >>> >>>> Roelof >>>> >>>> >>> >> >

April 18, 2019

Re: [Pharo-users] how to model this a better way

by Roelof Wobben

April 18, 2019

Re: [Pharo-users] how to model this a better way

by Richard Sargent

On Thu, Apr 18, 2019 at 10:33 AM Roelof Wobben <r.wobben(a)home.nl> wrote: > oke > > Maybe I understand something not right, > > Lets say we have this scenario. > > Robot is on position (0,0) > now it turns left so the robot faces East > I don't understand what position has to do with direction nor why that would be a problem. They are two distinct attributes. Point and Dictionary are sufficient classes to model the limited requirements of this exercise. You could model a new class DirectionVector which internalizes the Point used to provide the direction and provides its own name, eliminating the need for a look up of any kind. > or this scenario > > Robot is on position (0,0) > now it turns right so the robot faces west. > > it looks that dictionary cannot provide this answer. > or do I overlook something > > Roelof > > > > Op 18-4-2019 om 19:17 schreef Richard Sargent: > > On Thu, Apr 18, 2019 at 10:01 AM Roelof Wobben <r.wobben(a)home.nl> wrote: > >> yep, I have read that one >> but I never gets a answer how I can "convert" a point to something like >> north, east >> >> because the challenge wants this to be the answer : >> >> (Dictionary new >> add: 'direction' -> 'north'; >> add: >> 'position' >> -> >> (Dictionary new >> add: 'x' -> 0; >> add: 'y' -> 0; >> yourself); >> yourself) >> > > If you have previously defined a "representation map", you would be golden. > > e.g. > Dictionary new > at: self northDirectionVector put: 'north'; > at: self eastDirectionVector put: 'east'; > at: self southDirectionVector put: 'south'; > at: self westDirectionVector put: 'west'; > yourself. > > Then: > (Dictionary new > add: 'direction' -> (self directionRepresentationMap at: > self directionVector); > ... > > >> >> and I think I need then to use if then , which I try to avoid as much as >> possible. >> >> Roelof >> >> >> >> Op 18-4-2019 om 18:33 schreef Richard Sargent: >> >> On Thu, Apr 18, 2019 at 8:57 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >> >>> Hello, >>> >>> I know I have asked earlier but im still stuck on this one : >>> https://github.com/exercism/problem-specifications/blob/master/exercises/ro… >>> >>> I tried with all double dispatch but that will be a lot of duplicate >>> classes >>> >>> The problem I cannot solve right is that a robot can move or turn. when >>> a robot turns only the direction the robot is facing changes and the >>> position not. when a robot moves the facing direction stays the same but >>> the position changes. but the change is dependend on the facing. Also the >>> new facing direction is dependend on the old facing direction/ >>> How can I model this the best. >>> >>> I already have a object Robot that contains the facing direction and the >>> current position >>> or tried without it but then I use a lot of if then's >>> >>> >>> so it there a better way to model this problem so it will be all nice >>> and readable code. >>> >> >> If I remember correctly, Richard O'Keefe gave you a viable design. 1) Use >> a Point for your direction vector. 2) Use a second Point for your position. >> >> e.g. if you align the compass with a Cartesian plane, 0@1 is North, 0@-1 >> is South, 1@0 is East, and -1@0 is West. When you move, you add the >> direction vector to your current position. If you allow movements of >> greater than a single unit, you multiply the direction vector by the >> distance before adding that product to the position. >> >> >>> Roelof >>> >>> >> >

April 18, 2019

Re: [Pharo-users] how to model this a better way

by Roelof Wobben

Ben, I have such a dictionary in my first attempt to solve this one. and another one for the facing. Lets say we have this scenario: Robot begins at (0,0) facing north then it turns right so it faces west then it moves one step so the new position is (-1,0) then it turns left so it faces north again then it moves one step so theÂ new position is (-1,1) so if I see it , the position has nothing to do with the direction the robot is facing this is only important for finding out a new direction orÂ to find out if the x or the y needs to change. Roelof Op 18-4-2019 om 19:27 schreef Ben Coman: > map := Dictionary newFromPairs: { > 'north'. 0 @ 1 . > 'south'. 0 @ -1 . > 'east'. 1 @ 0 . > 'west' . -1 @ 0 }. > (map at: 'north') inspect. > (map keyAtValue: 0 @ -1) inspect

April 18, 2019

Re: [Pharo-users] how to model this a better way

by Roelof Wobben

April 18, 2019

Re: [Pharo-users] how to model this a better way

by Ben Coman

>> e.g. if you align the compass with a Cartesian plane, 0@1 is North, 0@-1 is South, 1@0 is East, and -1@0 is West. On Fri, 19 Apr 2019 at 01:01, Roelof Wobben <r.wobben(a)home.nl> wrote: > > yep, I have read that one > but I never gets a answer how I can "convert" a point to something like north, east Maybe you are looking for something like this... map := Dictionary newFromPairs: { 'north'. 0 @ 1 . 'south'. 0 @ -1 . 'east'. 1 @ 0 . 'west' . -1 @ 0 }. (map at: 'north') inspect. (map keyAtValue: 0 @ -1) inspect. cheers -ben > > because the challenge wants this to be the answer : > > (Dictionary new > add: 'direction' -> 'north'; > add: > 'position' > -> > (Dictionary new > add: 'x' -> 0; > add: 'y' -> 0; > yourself); > yourself) > > > and I think I need then to use if then , which I try to avoid as much as possible. > > Roelof > > > > Op 18-4-2019 om 18:33 schreef Richard Sargent: > > On Thu, Apr 18, 2019 at 8:57 AM Roelof Wobben <r.wobben(a)home.nl> wrote: >> >> Hello, >> >> I know I have asked earlier but im still stuck on this one : https://github.com/exercism/problem-specifications/blob/master/exercises/ro… >> >> I tried with all double dispatch but that will be a lot of duplicate classes >> >> The problem I cannot solve right is that a robot can move or turn. when a robot turns only the direction the robot is facing changes and the position not. when a robot moves the facing direction stays the same but the position changes. but the change is dependend on the facing. Also the new facing direction is dependend on the old facing direction/ >> How can I model this the best. >> >> I already have a object Robot that contains the facing direction and the current position >> or tried without it but then I use a lot of if then's >> >> >> so it there a better way to model this problem so it will be all nice and readable code. > > > If I remember correctly, Richard O'Keefe gave you a viable design. 1) Use a Point for your direction vector. 2) Use a second Point for your position. > > e.g. if you align the compass with a Cartesian plane, 0@1 is North, 0@-1 is South, 1@0 is East, and -1@0 is West. When you move, you add the direction vector to your current position. If you allow movements of greater than a single unit, you multiply the direction vector by the distance before adding that product to the position. > >> >> Roelof >> >

April 18, 2019

Re: [Pharo-users] how to model this a better way

by Richard Sargent

On Thu, Apr 18, 2019 at 10:01 AM Roelof Wobben <r.wobben(a)home.nl> wrote: > yep, I have read that one > but I never gets a answer how I can "convert" a point to something like > north, east > > because the challenge wants this to be the answer : > > (Dictionary new > add: 'direction' -> 'north'; > add: > 'position' > -> > (Dictionary new > add: 'x' -> 0; > add: 'y' -> 0; > yourself); > yourself) > If you have previously defined a "representation map", you would be golden. e.g. Dictionary new at: self northDirectionVector put: 'north'; at: self eastDirectionVector put: 'east'; at: self southDirectionVector put: 'south'; at: self westDirectionVector put: 'west'; yourself. Then: (Dictionary new add: 'direction' -> (self directionRepresentationMap at: self directionVector); ... > > and I think I need then to use if then , which I try to avoid as much as > possible. > > Roelof > > > > Op 18-4-2019 om 18:33 schreef Richard Sargent: > > On Thu, Apr 18, 2019 at 8:57 AM Roelof Wobben <r.wobben(a)home.nl> wrote: > >> Hello, >> >> I know I have asked earlier but im still stuck on this one : >> https://github.com/exercism/problem-specifications/blob/master/exercises/ro… >> >> I tried with all double dispatch but that will be a lot of duplicate >> classes >> >> The problem I cannot solve right is that a robot can move or turn. when a >> robot turns only the direction the robot is facing changes and the position >> not. when a robot moves the facing direction stays the same but the >> position changes. but the change is dependend on the facing. Also the new >> facing direction is dependend on the old facing direction/ >> How can I model this the best. >> >> I already have a object Robot that contains the facing direction and the >> current position >> or tried without it but then I use a lot of if then's >> >> >> so it there a better way to model this problem so it will be all nice >> and readable code. >> > > If I remember correctly, Richard O'Keefe gave you a viable design. 1) Use > a Point for your direction vector. 2) Use a second Point for your position. > > e.g. if you align the compass with a Cartesian plane, 0@1 is North, 0@-1 > is South, 1@0 is East, and -1@0 is West. When you move, you add the > direction vector to your current position. If you allow movements of > greater than a single unit, you multiply the direction vector by the > distance before adding that product to the position. > > >> Roelof >> >> >

April 18, 2019