CSE 505 -- Smalltalk Mini-Exercises

1. Write a Smalltalk expression to return true if x is either equal to 0 or if 10 divided by x equals y.
2. Let a be an array of some sort. Write a loop that prints every second element on an output stream strm. To get you started, here is some code that initializes a to an array with some objects, and that prints the first element on strm, and finally returns the contents of the stream.

     | a strm |
     strm := WriteStream with: (String new: 100).
     a := Array new: 10.
     a at: 1 put: 'fee fi fo fum'.
     a at: 2 put: 3.14159.
     a at: 3 put: 8.
     (a at: 2) printOn: strm.
     strm contents
   

3. Add a repeatUntil control structure to Smalltalk. Hint: this is trivial -- do it by defining a repeatUntil: method for BlockContext.
4. Consider the following Smalltalk class definition.

   Object subclass: #Octopus
      instanceVariableNames: 'myblock'
      classVariableNames: ''
      poolDictionaries: ''
   
   setValue: x
      myblock := [x].
   
   setBlock: y
      myblock := y.
   
   getValue
     ^ myblock value
   

   What is the result of evaluating the following code? (The value in each case will be the value of the last o getValue expression.)

         | o a |
      a := 3.
      o := Octopus new.
      o setValue: a.
      a := a+1.
      o getValue
   

   And what about this code?

         | o a b |
      a := 3.
      b := [a].
      o := Octopus new.
      o setBlock: b.
      a := a+1.
      o getValue