Let’s Play Objects

15
S.Ducasse 1 QuickTime™ TIFF (Uncompr are needed t Stéphane Ducasse [email protected] http://www.listic.univ-savoie.f r/~ducasse/ Let’s Play Objects

description

Let’s Play Objects. Outline. Simulate a LAN physically Set up a context for future chapters Exercises Some forward references to intriguate you. A LAN Simulator. A LAN contains nodes, workstations, printers, file servers. Packets are sent in a LAN and each node treats them differently. - PowerPoint PPT Presentation

Transcript of Let’s Play Objects

Page 1: Let’s Play Objects

S.Ducasse 1

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Stéphane [email protected]://www.listic.univ-savoie.fr/~ducasse/

Let’s Play Objects

Page 2: Let’s Play Objects

S.Ducasse 2

License: CC-Attribution-ShareAlike 2.0http://creativecommons.org/licenses/by-sa/2.0/

Page 3: Let’s Play Objects

S.Ducasse 3

Outline •Simulate a LAN physically•Set up a context for

• future chapters• Exercises

•Some forward references to intriguate you

Page 4: Let’s Play Objects

S.Ducasse 4

A LAN SimulatorA LAN contains nodes, workstations, printers, file servers. Packets are sent in a LAN and each node treats them differently.

macnode3

node2

pcnode1

lpr

Page 5: Let’s Play Objects

S.Ducasse 5

Three Kinds of ObjectsNode and its subclasses represent the entities that are connected to form a LAN. Packet represents the information that flows between Nodes.NetworkManager manages how the nodes are connected

Page 6: Let’s Play Objects

S.Ducasse 6

LAN Design

Node

WorkstationPrinter

NetworkManager

PacketaddresseecontentsoriginatorisSentBy: aNodeisAddressedTo: aNode

nameaccept: aPacketsend: aPackethasNextNode

originate: aPacketaccept: aPacket

print: aPacketaccept: aPacket

declareNode: aNodeundeclareNode: aNodeconnectNodes: anArrayOfAddressees nextNode

Page 7: Let’s Play Objects

S.Ducasse 7

Interactions Between Nodes

accept: aPacket

send: aPacket

nodePrinter aPacket node1

isAddressedTo: nodePrinter

accept: aPacket

print: aPacket

[true]

[false]

Page 8: Let’s Play Objects

S.Ducasse 8

Node and Packet Creation|macNode pcNode node1 printerNode node2 node3 packet|macNode := Workstation withName: #mac.pcNode := Workstation withName: #pc.node1 := Node withName: #node1.node2 := Node withName: #node2.node3 := Node withName: #node2.printerNode := Printer withName: #lpr.macNode nextNode: node1.node1 nextNode: pcNode.pcNode nextNode: node2.node3 nextNode: printerNode.lpr nextNode: macNode.

packet := Packet send: 'This packet travelled to' to: #lpr.

Page 9: Let’s Play Objects

S.Ducasse 9

Objects sends Messages• Message: 1 + 2

– receiver : 1 (an instance of SmallInteger)– selector: #+– arguments: 2

• Message: lpr nextNode: macNode– receiver lpr (an instance of LanPrinter)– selector: #nextNode: – arguments: macNode (an instance of Workstation)

• Message: Packet send: 'This packet travelled to' to: #lpr– receiver: Packet (a class)– selector: #send:to:– arguments: 'This packet travelled to' and #lpr

Page 10: Let’s Play Objects

S.Ducasse 10

Transmitting a Packet| aLan packet macNode|...macNode := aLan findNodeWithAddress: #mac.packet := Packet send: 'This packet travelled to

the printer' to: #lpr.macNode originate: packet.

-> mac sends a packet to pc -> pc sends a packet to node1-> node1 sends a packet to node2-> node2 sends a packet to node3-> node3 sends a packet to lpr-> lpr is printing -> this packet travelled to lpr

Page 11: Let’s Play Objects

S.Ducasse 11

How to Define a Class (Sq)• Fill the template:

NameOfSuperclass subclass: #NameOfClassinstanceVariableNames: 'instVarName1'classVariableNames: 'ClassVarName1 ClassVarName2'poolDictionaries: ''category: 'LAN’

• For example to create the class Packet

Object subclass: #PacketinstanceVariableNames: 'addressee originator

contents 'classVariableNames: ''poolDictionaries: ''category: 'LAN'

Page 12: Let’s Play Objects

S.Ducasse 12

Smalltalk defineClass: #Packet superclass: #{Object}

indexedType: #none private: false instanceVariableNames: 'addressee

originator contents' classInstanceVariableNames: ''

imports: ''category: 'LAN'

How to Define a Class (VW)

Page 13: Let’s Play Objects

S.Ducasse 13

How to define a method?message selector and argument names

"comment stating purpose of message"| temporary variable names |statements

LanPrinter>>accept: thePacket"If the packet is addressed to me, print it. Otherwise just behave like a normal node."

(thePacket isAddressedTo: self)ifTrue: [self print: thePacket] ifFalse: [super accept: thePacket]

Page 14: Let’s Play Objects

S.Ducasse 14

In JavaIn Java we would write void accept(thePacket Packet)/*If the packet is addressed to me, print it.

Otherwise just behave like a normal node.*/if (thePacket.isAddressedTo(this)){

this.print(thePacket)}else super.accept(thePacket)}

Page 15: Let’s Play Objects

S.Ducasse 15

SummaryDefine a classDefine a method


Let’s Play Jeopardy

Let’s Play Jeopardy

Let’s play BANKING!

Let’s play BANKING!

Let’s Play Hangman!

Let’s Play Hangman!

Let’s Play Jeopardy!!

Let’s Play Jeopardy!!

Let’s Play Ball!

Let’s Play Ball!

Let’s play snooker

Let’s play snooker

Let’s Play…..

Let’s Play…..

LET’S PLAY JEOPARDY!!

LET’S PLAY JEOPARDY!!

English Meadows Play Group Let’s Play!

English Meadows Play Group Let’s Play!

Let’s Play……….

Let’s Play……….

Let’s play soccer. play tennis play volleyball read play ... · B: Let’s play soccer. What are we doing today? Let’s play soccer. play tennis play volleyball read play baseball

Let’s play soccer. play tennis play volleyball read play ... · B: Let’s play soccer. What are we doing today? Let’s play soccer. play tennis play volleyball read play baseball

Let’s play…

Let’s play…

Let’s Play Jeopardy !

Let’s Play Jeopardy !

Let’s Play

Let’s Play

Let’s Play!

Let’s Play!

Let’s Play! - ed

Let’s Play! - ed

Let’s Play Hangman

Let’s Play Hangman

LET’S PLAY JEOPARDY!

LET’S PLAY JEOPARDY!