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

April 18, 2019


      On Thu, Apr 18, 2019 at 10:33 AM Roelof Wobben <r.wobben@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@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@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/rob...
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