Object-Oriented Programming?

² ³ I 0,1 November 18 500, CIS otaeFoundations Software 8November 18 a l2002 Fall I 500 CIS 1 ± ° ² ³ I 0,1 November 18 500, CIS § § § § rdn usin?Seyu TA. your See questions? Grading breakdown: grade Rough 556 in available to results go Midterm instead please 307 — Towne cancelled in afternoon K. this Max recitation 3PM Pierce’s Prof. 8 onsi ntre o WPE-I for on-target is points 58+ 54:C 35-49: B 50-64: A 65-80: 4 D/F 34: Administrivia 2 ± ° ² ³ I 0,1 November 18 500, CIS nt Objects to On 3 ± ° ² ³ I 0,1 November 18 500, CIS o tstm to time and it’s deﬁning Now for features. tools language developing programming weeks about 10 reasoning past the spent We’ve use hs ol o oehn oeambitious. more something for tools these AChangeofPace 4 ± ° ² ³ I 0,1 November 18 500, CIS Plan: 2. 1. (b) (a) eeo w ifrn nlsso hs features: these of analyses different two Develop object-oriented of features” programming “core characteristic some Identify A A agae(FahregtJava”) (“Featherweight language direct translation aesuy betoine programming object-oriented study: Case ihlvlfraiaino ipeobject-oriented simple a of formalization high-level , noalwrlvllanguage lower-level a into 5 ± ° ² ³ I 0,1 November 18 500, CIS a eudrto s“eie om”i oe-ee agaewt a with language lower-level features: a primitive in of forms” collection “derived rich as understood be can of features basic the of many how show to be languages object-oriented will goal ﬁrst Our subtyping recursion references records functions (higher-order) binding late super and (this) self inheritance state of encapsulation dispatch dynamic objects h rnltoa Analysis Translational The 6 ± ° ² ³ I 0,1 November 18 500, CIS hnw oet oecmlxfaue i atclr lse with classes particular, (in features well. complex very more ×eÐf works to analysis come translational we this When classes, and objects simple For ramn ntefloigchapter. following the in treatment ,i eoe esstsatr,laigu otemr direct more the to us leading satisfactory, less becomes it ), 7 ± ° ² ³ I 0,1 November 18 500, CIS History 8 ± ° ² ³ I 0,1 November 18 500, CIS Beta

Dylan Simula-67 CLOS Self Cecil Smalltalk 72, Smalltalk 80 Objective C, etc. Java C++ C# 9 ± ° ² ³ I 0,1 November 18 500, CIS Concepts 10 ± ° ² ³ I 0,1 November 18 500, CIS ht“s betoine programming? object-oriented “is” What h sec fObjects of Essence The 11 ± ° ² ³ I 0,1 November 18 500, CIS hsqeto a enasbeto eaefrdcds uharguments Such interesting. decades. very for seldom debate of and inconclusive subject always a are been has question This programming? object-oriented “is” What h sec fObjects of Essence The 11-a ± ° ² ³ I 0,1 November 18 500, CIS otO agae n ht oehr upr itntv n useful and by distinctive shared a are support together, that style. that, features programming core and languages some identify OO to most arguments easy Such is interesting. decades. it very However, for seldom debate of and inconclusive subject always a are been has question This programming? object-oriented “is” What h sec fObjects of Essence The 11-b ± ° ² ³ I 0,1 November 18 500, CIS neadfral(swe eapyafnto oa argument). an to function a apply the fixed we of being when objects Two than (as rather all itself, for object and the once on depends behavior is ensuing programming object-oriented of dispatch characteristic dynamic basic most the Perhaps prtos a eipeetditral in internally implemented be may operations) hna prto sivkdo nojc,the object, an on invoked is operation an when : aetype same yai dispatch Dynamic ie,rsodn otesm e of set same the to responding (i.e., opeeydifferent completely ways. 12 ± ° ² ³ I 0,1 November 18 500, CIS nms Olnugs ahojc ossso oeitra state internal state. some of that consists object each encapsulated languages, OO most In § § tt niil ncesbefo usd h object the outside from inaccessible / invisible state methods to accessible directly state ihacleto fmto mlmnain prtn on operating implementations method of collection a with Encapsulation 13 ± ° ² ³ I 0,1 November 18 500, CIS agae r upiigysmlrt hs n“antem Olanguages. OO “mainstream” in those to multi-method similar in surprisingly arising higher-level are etc.) the languages inheritance, different, (classes, quite idioms are programming mechanisms basic their Although on instead, polymorphism. based, are languages These ntesneta hr r eea Olnugs(.. LS ya,and Dylan, CLOS, (e.g., languages OO several dispatch, do are dynamic that there than Cecil) that fundamental sense less the little in a arguably is Encapsulation not naslt tt ihmethods. with state encapsulate ient:encapsulation note: Side multi-methods omo ad-hoc of form a , 14 ± ° ² ³ I 0,1 November 18 500, CIS oehtdfeetfr fifrainhdn sebde nthe in embodied is hiding an information of of of notion form form different a somewhat is A objects by offered methods hiding with information state of encapsulation The btatdt type data abstract . ient:Ojcsv.ADTs vs. Objects note: Side (ADT). 15 ± ° ² ³ I 0,1 November 18 500, CIS nATcomprises: ADT An oeo esasnnmfr“bettp. hsi notnt,sneit since unfortunate, is as This used type.” often concepts. “object different is rather for type” two data synonym “abstract confuses a term less the or community, more OO the in N.b. dispatch. dynamic and advantages. no have type — representation styles operations (hidden) Both the one of just implementation is type. one there abstract just that the the in of by different provided elements operations manipulate But directly the to only allowed that are in ADT encapsulation OO to Similar § § olcino prtosfrcetn n aiuaigeeet of elements manipulating and creating for type operations of collection A A hidden X . ersnaintype representation ient:Ojcsv.ADTs vs. Objects note: Side X 16 ± ° ² ³ I 0,1 November 18 500, CIS rt n ic fcd htoeae nfrl nayojc whose object as any can good we on as uniformly polymorphism: least operates of “at that form is code useful interface of and piece natural one a write to rise gives This relation. their subtype of a representation. types into internal the naturally the (and fit include interfaces it not Object on just does performed is it be object results); can an and that of parameters operations terminology) of Smalltalk set in the “interface” (or “type” The h prtosin operations the nitraelsigmr prtosi bte”ta n listing one than “better” is operations. operations fewer more listing interface An Á ). Subtyping Á ie,ayojc htspot tleast at supports that object any (i.e., ” 17 ± ° ² ³ I 0,1 November 18 500, CIS oaoddpiaino oe att rt h mlmnain fthese of implementations = place. the one write just to in want behaviors code, of not duplication (though avoid behaviors. To typically their will of interfaces parts their share of always) parts share that Objects µ inheritance Inheritance 18 ± ° ² ³ I 0,1 November 18 500, CIS ls sadt tutr htcnbe can that structure data a is class A inheritance: of mechanism Basic eie yrfiigtebhvo feitn objects. existing of behavior the fairly refining fundamentally by (but derived alternative called an mechanism, offer similar) languages OO some N.b.: § § refined instantiated ocet e lse (“subclasses”) classes new create to ocet e bet (“instances”) objects new create to delegation Inheritance classes hc losnwojcst be to objects new allows which , 19 ± ° ² ³ I 0,1 November 18 500, CIS otO agae fe netnino h ai ehns fclasses of mechanism basic the of called extension inheritance an and offer languages OO Most aebnigalw ehdwti ls ocl nte ehdvaa via method another call to class a within “pseudo-variable” method special a allows binding Late odfie(sw ilse n ouetseul.Frti esn tis it reason, this For tastefully. use to both tricky, practice. and rather in see) is deprecated will binding sometimes we late (as situations, define many to in useful quite Though automatically method first the well. of as behavior changes the then subclass, some aebinding late ×eÐf aebinding Late ftescn ehdi vridnby overridden is method second the If . or pnrecursion open . 20 ± ° ² ³ I 0,1 November 18 500, CIS etn ont details... to down Getting 21 ± ° ² ³ I 0,1 November 18 500, CIS = CÓÙÒØeÖ where c µ = c ÐeØ : ßgeØ CÓÙÒØeÖ iÒc = Ü ßgeØ:ÍÒiØ = = = Öef _:ÍÒiØº _:ÍÒiØº ½ iÒ ! ÆaØ¸ Ü:=×Ùcc´!Üµ}; !Ü¸ iÒc:ÍÒiØ Objects ! ÍÒiØ} 22 ± ° ² ³ I 0,1 November 18 500, CIS = íÒc¿ = iÒc¿ µ µ 7 iÒc¿ = c; c:CÓÙÒØeÖº : cºgeØ CÓÙÒØeÖ ÙÒiØµ; ! ćºiÒc ÍÒiØ ÙÒiØ; Objects cºiÒc ÙÒiØ; cºiÒc ÙÒiØµ; 23 ± ° ² ³ I 0,1 November 18 500, CIS = ÒeÛCÓÙÒØeÖ µ _:ÍÒiØº ÒeÛCÓÙÒØeÖ = ÐeØ ßgeØ : iÒc Ü ÍÒiØ = = = Öef ! _:ÍÒiØº _:ÍÒiØº betGenerators Object ½ CÓÙÒØeÖ iÒ Ü:=×Ùcc´!Üµ}; !Ü¸ 24 ± ° ² ³ I 0,1 November 18 500, CIS = ÒeÛÊe×eØCÓÙÒØeÖ Êe×eØCÓÙÒØeÖ µ _:ÍÒiØº ÒeÛÊe×eØCÓÙÒØeÖ ÐeØ = ßgeØ Öe×eØ iÒc ßgeØ:ÍÒiØ Ü = = Öef : = = = ÍÒiØ ½ ! _:ÍÒiØº _:ÍÒiØº _:ÍÒiØº iÒ ÆaØ¸ ! Subtyping Êe×eØCÓÙÒØeÖ iÒc:ÍÒiØ Ü:=½}; Ü:=×Ùcc´!Üµ¸ !Ü¸ ! ÍÒiØ¸ Öe×eØ:ÍÒiØ ! ÍÒiØ}; 25 ± ° ² ³ I 0,1 November 18 500, CIS = íÒc¿ Öc µ = 4 ÒeÛÊe×eØCÓÙÒØeÖ Öc; ÖcºÖe×eØ ÙÒiØ; ÙÒiØ; iÒc¿ Subtyping Öc; ÖcºgeØ ÙÒiØµ; 26 ± ° ² ³ I 0,1 November 18 500, CIS twl ecnein ltr ogopteeit igerecord. single a into these group to (later) convenient be will It c of consist objects most of states the of cell, number reference a single a than Rather CÓÙÒØeÖÊeÔ = ÐeØ ßgeØ iÒc Ö = = = = ßÜ=Öef ntnevariables instance ßÜ: _:ÍÒiØº _:ÍÒiØº Êef ruigIsac Variables Instance Grouping ½} ÆaØ}; iÒ ÖºÜ:=×Ùcc´!´ÖºÜµµ}; !´ÖºÜµ¸ or fields . 27 ± ° ² ³ I 0,1 November 18 500, CIS h entosof definitions The hsvoae ai rnil fsfwr engineering: software of principle basic a violates This o the for ahpeeo eairsol eipeetdi utoepaein place one just in implemented be code. should the behavior of piece Each Öe×eØ method. ÒeÛCÓÙÒØeÖ ipeClasses Simple and ÒeÛÊe×eØCÓÙÒØeÖ r dnia except identical are 28 ± ° ² ³ I 0,1 November 18 500, CIS da ol ejs euetemtoso oeeitn bett ul a build to object existing some eÖ ÒØ Öe×eØCÓÙÒØeÖFÖÓÑCÓÙ of methods the object? re-use new just we could Idea: c:CÓÙÒØeÖº ßgeØ ÐeØ Öe×eØ iÒc Ü = = = = Öef cºiÒç cºgeØ¸ esn Methods Reusing = _:ÍÒiØº ½ iÒ Ü:=½}; 29 ± ° ² ³ I 0,1 November 18 500, CIS o hsdentwr rprybcuethe because properly work doesn’t This No: a build to object existing some eÖ ÒØ Öe×eØCÓÙÒØeÖFÖÓÑCÓÙ of methods the object? re-use new just we could Idea: cest h ntnevariable instance the to access c:CÓÙÒØeÖº ßgeØ ÐeØ Öe×eØ iÒc Ü = = = = Öef cºiÒç cºgeØ¸ esn Methods Reusing = _:ÍÒiØº ½ iÒ Ü fteoiia counter. original the of Ü:=½}; Öe×eØ ehdde o have not does method = µ classes 29-a ± ° ² ³ I 0,1 November 18 500, CIS ls sarntm aasrcueta a be can that structure data run-time a is class A 2. 1. instantiated extended oyednwclasses new yield to oyednwobjects new yield to Classes 30 ± ° ² ³ I 0,1 November 18 500, CIS = = rmteato idn hs ehd oapriua e finstance of set particular a to ÒeÛCÓÙÒØeÖ methods these binding variables: of act the from to is do to methods need the we cÓÙÒØeÖCÐa×× of what definition before, the observed separate we problem the avoid To µ µ _:ÍÒiØº Ö:CÓÙÒØeÖÊeÔº ÒeÛCÓÙÒØeÖ cÓÙÒØeÖCÐa×× ßgeØ iÒc = = = ÐeØ _:ÍÒiØº _:ÍÒiØº = cÓÙÒØeÖCÐa×× : Ö ÍÒiØ : = CÓÙÒØeÖÊeÔ ßÜ=Öef ÖºÜ:=×Ùcc´!´ÖºÜµµ}; !´ÖºÜµ¸ ! CÓÙÒØeÖ ½} Ö; iÒ Classes ! CÓÙÒØeÖ 31 ± ° ² ³ I 0,1 November 18 500, CIS = ÒeÛÊe×eØCÓÙÒØeÖ = Öe×eØCÓÙÒØeÖCÐa×× µ µ _:ÍÒiØº Ö:CÓÙÒØeÖÊeÔº ÒeÛÊe×eØCÓÙÒØeÖ Öe×eØCÓÙÒØeÖCÐa×× ÐeØ ßgeØ Öe×eØ iÒc ×ÙÔeÖ ÐeØ = = = = ×ÙÔeÖºiÒç ×ÙÔeÖºgeØ¸ Ö = cÓÙÒØeÖCÐa×× _:ÍÒiØº = = ßÜ=Öef : ÍÒiØ : enn Subclass a Defining CÓÙÒØeÖÊeÔ ÖºÜ:=½}; ½} ! Ö iÒ Êe×eØCÓÙÒØeÖ iÒ Öe×eØCÓÙÒØeÖCÐa×× ! Êe×eØCÓÙÒØeÖ Ö; 32 ± ° ² ³ I 0,1 November 18 500, CIS = backÙÔCÓÙÒØeÖCÐa×× BackÙÔCÓÙÒØeÖÊeÔ ngnrl hnw en ucasw ilwn oadnwinstances new add to want BackÙÔCÓÙÒØeÖ will we representation. subclass its a to define variables we when general, In µ Ö:BackÙÔCÓÙÒØeÖÊeÔº backÙÔCÓÙÒØeÖCÐa×× ÐeØ ßgeØ backÙÔ Öe×eØ iÒc ×ÙÔeÖ ======Öe×eØCÓÙÒØeÖCÐa×× ßgeØ:ÍÒiØ ×ÙÔeÖºiÒç ×ÙÔeÖºgeØ¸ = Öe×eØ:ÍÒiØ _:ÍÒiØº _:ÍÒiØº digisac variables instance Adding = ßÜ: : Êef BackÙÔCÓÙÒØeÖÊeÔ ! Öºb:=!´ÖºÜµ}; ÖºÜ:=!´Öºbµ¸ ! ÆaØ¸ ÆaØ¸ ÍÒiØ¸ iÒc:ÍÒiØ b: Ö backÙÔ: Êef iÒ ÆaØ}; ! ÍÒiØ¸ ! ÍÒiØ BackÙÔCÓÙÒØeÖ ! ÍÒiØ}; 33 ± ° ² ³ I 0,1 November 18 500, CIS backÙÔCÓÙÒØeÖCÐa×× Notes: § § Ö:BackÙÔCÓÙÒØeÖÊeÔº utpn sesnilhr i h ento of definition the (in here essential is subtyping backÙÔCÓÙÒØeÖCÐa×× new ÐeØ ßgeØ Öe×eØ backÙÔ Öe×eØ iÒc ×ÙÔeÖ h ento of definition the ) = = = = = Öe×eØCÓÙÒØeÖCÐa×× ×ÙÔeÖºiÒç ×ÙÔeÖºgeØ¸ _:ÍÒiØº _:ÍÒiØº = ohetns(with extends both Öºb:=!´ÖºÜµ}; ÖºÜ:=!´Öºbµ¸ cÓÙÒØeÖCÐa×× Ö iÒ backÙÔ n vrie wt a (with overrides and ) ×ÙÔeÖ ) 34 ± ° ² ³ I 0,1 November 18 500, CIS = ofis aku h urn tt.W a vi oyn h oefor code ×× Ða fÙÒÒÝBackÙÔCÓÙÒØeÖC the copying avoid to can We call every state. wanted current we the that backÙÔ up example) back the first of to sake the (for Suppose µ Ö:BackÙÔCÓÙÒØeÖÊeÔº ÙÒBcÙCÙØÖÐa × a× fÙÒÒÝBackÙÔCÓÙÒØeÖCÐ ÐeØ ymaking by ßgeØ backÙÔ Öe×eØ iÒc ×ÙÔeÖ = = = ×ÙÔeÖºgeØ¸ = = _:ÍÒiØº ×ÙÔeÖºÖe×eØ¸ backÙÔCÓÙÒØeÖCÐa×× ×ÙÔeÖºbackÙÔ}; iÒc s the use ´×ÙÔeÖºbackÙÔ = Calling : backÙÔ BackÙÔCÓÙÒØeÖÊeÔ Ö ×ÙÔeÖ and iÒ ÙÒiØ; iÒc ×ÙÔeÖºiÒc ehd from methods ! BackÙÔCÓÙÒØeÖ ÙÒiØµ¸ ×ÙÔeÖ . iÒc 35 ± °