CLASCAL REFERENCE MANUAL for the LISA 1N First Dratt~ March· 9th , MCMLXXXIII by Da.vid Casseres IApple Co"puter. Inc. 198J Cla.sca1 Reference ManuaJ CONTENTS 1 Introduction to Clascal Concepts 1.1 Class-Types ....•..... 1.2 Objects ............ . 1.3 The Class H1erarchy .... . 1.4 ~~ce ........... . 1.5 Assignment-Compa;tibillty of Objects Expa.ns1on ofEx1st1ng Pasca.1. Syntax .. 'Def1rdng a Class .......................... . l)ef'ining a Metl\.od . • • • • • • . . . • . • • • • . • . • • • . • • • • . .......... 2 3 4 4.1 4.2 4.3 4.4 4.5 4.6 5 6 'l OverrldingInher1tedMethods ••• Self-Reference via. the Self Pseudova.ria.ble Self-Reference via a Class-Identif1er Cla.sswid.e Methods Abstra.ctMethods • The New Metl\.od Class Object .•••••. Objects as Handles ...... . $H+ a.n.d$H- Compiler Commands Appendix A:· Sample lJstings ............. . 1 1 1 . . •. 2 2 3 3 •. 6 9 9 9 11 13 13 14 14 15 16 A-l Reference Manual Cla.sca.J 1 Introduction to Clascal Concepts Clascal is a set of extensions to Pascal on the Lisa. These extensions support "object-oriented" programming in a style th.a.t somewhat resembles SIMULA and SmalltaJk. The purpose is to provide a very highlevel interface to code libraries, allowing the user program to perform highly complicated functions with simple eaJ.ls, while still reta.irrlng flexibility . 1.1 Class-Types Cla.sealis ba.sed on a new category of user-def1ned types called clasS'" types. An individual class-type is referred to as a aJass. A cla.ss-type is a klnd of S'trUctured-type, resembling a reeord-type in that it contains na.med fields. A class can have two kinds of fields: • 1)8,:ta. Oelds are like the fields of a record; they. contain variable data, and each data field has its own type. • .Methods are procedures and functions. The fields are referenced lUte fields of a record, using a period and a field-identlf1er (or a w1th-statement that references a. field-identlf1er). For' exa.mple, it. area. identi:f1es a· field· defined in class Triangle, and c:rntTria:ngleis decla:rec:1 by va.r c:rntTr.ia.ngle: Tr.ia.ngle; then crntTrla.ngle. 8J'."e& is a reference to the area. field of cri\.tTrla.ngle. If azea. is a data. field, then crntTr.ia.ngle. area. is a va.ria.ble-referen.c:e; if area. is a. method, then crntTrla.ngle.area. is either a proceduresta.ternent or a. :t\mction-ca.ll. A class-type is declared in the interface-part of a unit, and is supported by a .method-block in th.eimplementation-part of the same unit. Section 3 gives the syntax for class-types and method-blocks. 12 Objects A class defines the behavior (data. fields and methods) of its objects:. Each objeetis an .tnsta.nce of the class tha.t def1nes its behavior. Each object is stored. in a. dyn~ca.lly alloca.ted.,pot.entially reloeatable data area. w1th,1n a heap. An. object of a given class is created by the new method defined. for that class; .this method returns a newlY created object of the cl.a.ss(see Seetl.on <4.6). …

We are looking forward to seeing you Monday· mom~ng at~8:30'Inthe' " Mariani .Training Room3rd" Floor Mariani Building Architecture of the Personal Office System ~. -- ~ .;; ~~ 'r~j;ir ~k~~~~ij t:~::~:=:j ·r=I· .: ;:, : ," ..:. . :,:<. . .~ :::~. I!~'r_' - .' . . :. .'. . ' .. ~~~-B- i:t" ~ ~ ~ Power I/O Board Supply CPU Board Memory ·Board Video Board ,Expan . Slots Peripherals etc. l • 2 ~rial (RS-232) ports • 1 panillel port • 3 .expansion· slots . • video output • clocklcalendar • paraltster memory • speaker :: -- ·......... ", I , @ Operating System * Single-User * Multi-Tasking * Priority Scheduling * Interrupt-Driven M Byte-Stream I/O Model Inter-Task Communication M - Shared Files - Shared Data - Pipes - Event Channels * Demand Fetching Of Code * Automatic Stack Expansion . * Redundant, Distributed Directory FD F SYS I EM REDUNDANCY I-ELPS SCAVENGER RE~T DlR'ECTORIES IN CASE OF POYIER FAlLUP£ MAS I ER DIRECTORY 1 PER DISK FILE NME... 10, TYPE, 10 I~nCN FD...E HINT (SAVED WITH FD..E) •. SECTOA HINT 1 PER FD...E NAnE. . TYPE DATE ACCfSSED, COPY PROTECTION, USER-DEfINABlE TYPES 1 PER SECTOR gCTOR HINT 10, INCARNATION, REt FILE POSH, DATA SI~ RELIABILITY FLAGS DATA ....,. ~ Jb. ..... ......... h. ...... . . 4sa Workshop • Keyboard oriented Intmface (cwlently) • Includes: Mc4 &Se oriented Text Editor La q sages (Pascal. ESic, Cobol) 68000 Assenlbler Linker Devel.opIlelt Utili~ • twachine lartguage ~ Syntbolic Procedlm-e ~llSS Disassa I tbler • @ -' Lisa Pascal Language If Desired Compatibilities - Standard Pascal (Jensen & Wirth) - UCSD Pascal (Apple II ar~ //1) - ISO Standard Pascal - Parametric Procedures M ~jor Extensions - 32 Bit Integers (LongInt Type) - @ Operator (address of) - Separate Compilations (UCSD Units) - Control of Physical Segmentation - Classes (e.g. Simula-67, Smalltalk) - Debugging Aids M' Ql:Ja.1ity of Code Generated - 16 Bit Address Offsets . - "Hot" Variables in Registers :! '\i"';' .. ,.,.,,;:;:;.;:;';:',;;;:::::;:,.;:;:;:;:::::;.,:::;:;.:.::,,:,,::::.:.: .. :;.::;::.:.;.:.:,;:',;.;:;.:.:::':';:::::;.::;::,:.;,::::;,:, .. :.:.:.:.:.:'. :':':::::':';';':"'::;:;:::::;.::;.; .. :;.:.;::,;.;.:::.::;:;:.::.;,:.:.::)~; Libraries Application FUer corrm SCroll Bar f'1gr .AJert ~ Cl1pBoard Mgr Print Library Field Editor Print ~ I j oata Base Intrtn !' Storage Allccator ! - - - - - - + - - - i FontMgt' II ~: Applications make calls to many different library units. ~: :; H n ~i ~-----------......--~-----......-~j \:.:.:;;.:::::.::;.,,;.;:,:. :-::::::,:.:::::,::-:::::: .. ::,-:........ ... ::,.:' ':"'" '-:":;:::::'.:-: . '. :;. :';.:-.' ' .. ;..-: ..... : ..... ' . ' ; ' ~ .: .. :,:;.. Storage l\Aanager pointer .... ,- .... ncn-relocatable blccX relccatable block ClipBoard Used to share data, cut & paste notation I,: .cut from here I~-te to here T I I ~ ~_~. .J: : : ;~ := -~=~:I=~I : '---""""-("""r!"'1 "i M.~…