An Introduction to Objecet-Oriented Programming.pdf

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1、Chapter1ThinkingObject-OrientedAlthoughthefundamentalfeaturesofwhatwenowcallobject-orientedprogram-mingwereinventedinthe1960's,objectorientedlanguagesreallycametotheattentionofthecomputingpublic-at-largeinthe1980's.Twoseminaleventswerethepublicationofawidely-readissueofByte(August1981)thatdescr

2、ibedtheprogramminglanguageSmalltalk,andtherstinternationalconferenceonobject-orientedprogramminglanguagesandapplications,heldinPortland,Ore-gonin1986.Now,almosttwentyyearslater,itisstillthecasethat,asInotedinthersteditionofthisbook(in1991):Object-orientedprogramming(OOP)hasbecomeexceedinglypo

3、p-ularinthepastfewyears.Softwareproducersrushtoreleaseobject-orientedversionsoftheirproducts.Countlessbooksandspecialis-suesofacademicandtradejournalshaveappearedonthesubject.Studentsstrivetolistexperienceinobject-orientedprogramming"ontheirresumes.Tojudgefromthisfranticactivity,object-orien

4、tedprogrammingisbeinggreetedwithevenmoreenthusiasmthanwesawheraldingearlierrevolutionaryideas,suchasstructuredpro-gramming"orexpertsystems."Myintentinthesersttwochaptersistoinvestigateandexplaintheba-sicprinciplesofobject-orientedprogramming,andindoingsotoillustratethefollowingtwoproposition

5、s:OOPisarevolutionaryidea,totallyunlikeanythingthathascomebeforeinprogramming.OOPisanevolutionarystep,followingnaturallyontheheelsofearlierprogrammingabstractions.12CHAPTER1.THINKINGOBJECT-ORIENTED1.1WhyIsOOPPopular?Thereareanumberofimportantreasonswhyinthepasttwodecadesobject-orientedprogram

6、minghasbecomethedominantprogrammingparadigm.Object-orientedprogrammingscalesverywell,fromthemosttrivialofproblemstothemostcomplextasks.Itprovidesaformofabstractionthatresonateswithtech-niquespeopleusetosolveproblemsintheireverydaylife.Andformostofthedominantobject-orientedlanguagesthereareaninc

7、reasinglylargenumberoflibrariesthatassistinthedevelopmentofapplicationsformanydomains.Object-orientedprogrammingisjustthelatestinalongseriesofsolutionsthathavebeenproposedtohelpsolvethesoftwarecrisis."Atheart,thesoftwarecrisissim