Student Originated Software 1997-1998 Fall Quarter
		A Software Engineering Course at The Evergreen State College

Student Originated Software Object-Oriented Programming (Smalltalk) Lecture 1a Programming Language Paradigms.... what do we mean by this term? what are they? (and give some examples...) imperative/procedural functional OO logic & constraint concurrent/distributed other ways to categorize programming languages? high/lo level 4GL, 3GL structured/not typed/not compiled/interpreted (one-pass, several pass) 'complete'/ not lazy evaluation side effects/not scoped/not what do we take in account when we select a programming language for a system: is it available? (or, affordable) do we know it? is it appropriate to the application? how well does it contribute to the software development at hand? what factors in selecting a language _to teach_ how is it to learn? does it have pedagogical value? will the students like it? will it be useful to them? directly, indirectly? (can we support it, and afford it) distinguish between concept, ability, skill why OO? why smalltalk? purely OO - objects all the way down dynamically typed multiplatform, interpreted, programming environment extensive library A VERY USEFUL LANGUAGE (INCREASINGLY POPULAR, IN SPITE OF JAVA) ----------- advice: smalltalk learning curve be prepared for culture shock (not for the waterfall model!) start off small explore and work interactively be prepared to throw code away get some help -- work with your partner! objects what's an object: code + data methods encapsulate variables invoking methods? objects send, receive messages; sender, receiver; defining objects - classes and instances inheritance, overriding, polymorphism (next week) using models for software development - modeling the real world! models real world objects - data, plus behavior, relationships about objects about smalltalk history structure - development environment class library a language what is your model of the stored program? (say, a C program?) program (code), and _state_ what do you think it looks like with smalltak? you are adding code dynamically, and creating objects the smalltalk virtual machine -- interprets code as it comes in "the image" -- where code and object instances are stored implementation (visualworks) the Smalltalk Virtual Machine (your image is its memory) the development environment (your classes + class library) (this is why ST is so portable!) next week - where these things live.... the language.... naming conventions - height, myHeight; Book, aBook; Employee, anEmployee literals and constants numbers strings symbols and arrays (inspect an array) constants true, false (vs. True, False) nil UndefinedObject variables - Smalltalk variables are typeless the temporary variable <origin> - can hold anything! | origin | origin := Date today. origin := 5. origin := 'nature'. origin := origin. (next week - class varibles) sending messages MyStorageSystem initialize. aSquare increaseSizeBy: 2. wendy employ: 'Shannon' as 'a Smalltalk Programmer' Database open: 'students.dat' using: key rwMode: 7. message separator - '.' sender, receiver; self. assignment ^true. Total := net + tax. aSeminar := Seminar with: people size:15. dougsSeminar := aSeminar. | origin | origin := 3+5. origin := 'apple' . Transcript cr; show: origin. every message expression has a value. combining messages. chaining aTriangle height asInteger. unary, binary, keyword unary, binary, keyword; left to right. ()s change order! MyCollection add: Pyramid new initialize. (you don't need to know what this means to give its eval order) (book openAtPage: 1+2*3) print cascading messages diskController reset intialize startRunning. diskController reset; intialize; startRunning. (most methods return self, usually by default, but not always!) about visual works (minimal subset) launcher (aka main window) workspace browser (to look at classes) the transcript ho1 getting started on smalltalk in the lab (shannon) demo1 - in class launcher, main window (aka transcript) briefly explain each menu and each icon what we'll use today - main window, workspace workspace select function (editing), operate function (undo), opening another workspace select text (drag, double click - word, line; shift click) getting a printout.... Transcript cr. Transcript show: 'Hello world!' what are the messages, what kinds of messages... demo1 - in lab running visual works HERE demo2 browsing the class hierarchy SAVING YOUR IMAGE....file-out-as don't save in the default location use a fully qualified file name must use file settings... [ SOS Home Page | Case Study | Year Long Projects | OOP ]