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smalltalksqueak

How to make a Squeak class from scratch?

I want to make a simple program in Squeak that calculates the distance between a couple of points, but I would not like to use the class Point that is already defined. So far I have the following:

enter image description here

The getter and setter methods of x and y have been auto generated:

x ^ x

x: anObject x := anObject.

and the distance method I programmed is the following: enter image description here

distance:aPoint
    "comment stating purpose of message"

    |dx dy |
    dx:=aPoint x - x.
    dy:=aPoint y - y.
    ^ (dx*dx+dy*dy) sqrt.

now I open a workspace and try to print out the results:

obj1:=PointS new.
obj1 x:3 y:4.
obj2:=PointS new.
obj2 x:5 y:6.
d:=obj1 distance obj2
UIManager default inform: 'Converted amount: ',d.

but the result I get is the following:

enter image description here

What am I missing?

Solution

  • Try replacing the following:

    obj1 x:3 y:4.

    With this:

    obj1 x:3; y:4.

    Basically, you are sending the message #x:y: but you don't have a method with that name. Instead you have a method #x: and another method #y:, so you need to make two separate calls to the same object (which is done with the cascade operator (#;).