MyQueue

CS 313 Smalltalk example


Class MyQueue
=============
Object subclass:#MyQueue
        instanceVariableNames:'data'
        classVariableNames:''
        poolDictionaries:''
        category:'DanielsClasses'


Class method
------------

new
    "create new instance and send it the 'init' message"

    ^ super new init


Instance methods
----------------

init
    "initialize data (called by 'new')"

    data := OrderedCollection new


first
    "return first element in queue without removing it"

    ^ data first


enqueue: anObject
    "add anObject to end of queue"

    data add: anObject


dequeue
    "remove element from front of queue and return it"

    ^ data removeFirst



Testing and sample output
=========================

|q| q := MyQueue new.
'enqueue: 1' printCR. q enqueue: 1 .
'first = ' print. q first printCR.
'enqueue: 2.0' printCR. q enqueue: 2.0 .
'first = ' print. q first printCR.
'enqueue: ''drei''' printCR. q enqueue: 'drei'.
'first = ' print. q first printCR.
'dequeue = ' print. q dequeue printCR.
'dequeue = ' print. q dequeue printCR.
'enqueue: #four' printCR. q enqueue: #four.
'first = ' print. q first printCR.
'dequeue =
' print. q dequeue printCR.
'dequeue = ' print. q dequeue printCR.

output (produced using "doIt" on the code above):
-------------------------------------------------

enqueue: 1
first = 1
enqueue: 2.0
first = 1
enqueue: 'drei'
first = 1
dequeue = 1
dequeue = 2.0
enqueue: #four
first = drei
dequeue = drei
dequeue = four