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Introducere

Introducere. Paradigme de programare Mihai Zaharia. Obiectivele cursului. Intelegerea principalelor paradigme de programare folosite in dezvoltarea aplicatiilor la aceasta ora. Familiarizarea cu diferite limbaje de programare care implementeaza una sau mai multe paradigme simultan

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Introducere

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  1. Introducere Paradigme de programare Mihai Zaharia

  2. Obiectivelecursului • Intelegerea principalelor paradigme de programare folosite in dezvoltarea aplicatiilor la aceasta ora. • Familiarizarea cu diferite limbaje de programare care implementeaza una sau mai multe paradigme simultan • Stabilirea tipurilor de probleme unde sunt folosite diverse paradigme functie de context • Invatarea unor instrumente noi de programare • Limbajele care vor fi folositea de-a lungul cursului sunt • UML • C/C++ • Java, • Java Beans • LabWindows • Python • Haskel • Prolog

  3. Criteriifolosite in evaluareaactivitatii • Participareala orele de curs si de laborator: • Neparticiparea la maimult de 14% din laboratoare conduce la refacereadisciplinei • Activitatea de laborator(nu e de ajunssaitiaducicorpul la laborator = participare) 25% • Temeacasala majoritatealaboratorelor 25% • Examen final 50% (este o singura nota) defalcatastfel: • Proba de laborator – ELIMINATORIE 25% cu biletesi 2 ore maxim la dispozitie. Un subiect din douatrebuiesa fie indeplinit integral pentru a se putea nota (min 5) • Probateoretica– 25% - test docimologic - continesiintrebari cu caracterpracticspecficelaboratorului (min 5)

  4. Indatoririlestudentului Cititimaterialelerecomandate cu o ziinainte de fiecare curs – elaborati o lista de intrebari eventual Rezolvatitemelepeacasa in saptamana in care le-atiprimit Participatila cursuri (suportul de curs livratvacontinenumaidesenele/cod din slide-uri) Rezervati un minim de 2-4 ore de studiu individual pesaptamanapentruaceastamaterie Verificatiintelegereateoreticasipracticaa notiunilorasimilateprinajutareacolegilor cu raspunsuri legate de parteateoreticasauajutor (nu temacopiata) in rezolvareaproblemelor practice Caviitoriinginerieste de asteptatesaRespectaticodul etic minim al IEEE http://www.ieee.org/about/corporate/governance/p7-8.html

  5. Sintaxa • Definestesimbolurilesigramaticaunuilimbaj • BNF sau • EBNF if-statement ::= if ( expression ) statement-block [ else statement-block ] statement-block ::= statement ';' | '{' statement ';' [...] '}' statement ::= if-statement | assignment-statement | while-statement | ...etc...

  6. Strategii de implementare Compilator: Interpretor: Hibrid:

  7. Compilareaunui program file.c main() { printf("hello"); exit(0); } Cod sursa Preprocesor AnalizorLexical, etc file.obj .sym printf FE048C7138 029845AAAF ... Object Code Compilator Executable Program Link-Editor printf.obj <obj. code for printf function> file.exe <hardware instructions> Biblioteci (pentru cod obiect

  8. ‘Escu.java Java: o strategiehibrida Biblioteci Executare program Sunt ‘escu! javac Hello.class java Program sursa Java compilator byte code • MVJ: • Verificarebyte cod • - Incarcareclase • - interpretor Java Runtime Environment (JRE)

  9. public int cmmdc ( int v# ) // eroare lexicala { int z = value y = v; while ( y >= 0 ) { int t = y; y = z % y; z = t; } return y; } Exemple de erori (Java):

  10. Executiainstructiunilorpe un CPU 0010110010100010 0001011110000000 0010110000011000 1101100001011001 0011001010001011 0000011101001111 1101100001100001 0010110100010001 0001011100001110 …etc…

  11. Executareaunui program Registriinterni RAM Cache Contorulprogramului

  12. Ceinstructiuni de bazapoateinterpreta un procesor? LOAD SAVE MOVE ADD MULT COMPARE TEST JUMPTO

  13. 0: iconst_2 //incepe for 1: istore_1 2: iload_1 3: sipush 1000 6: if_icmpge 44 //comparatia cu 1000 9: iconst_2 //incepe for 10: istore_2 11: iload_2 12: iload_1 13: if_icmpge 31 // compartia cu i 16: iload_1 //incepe if 17: iload_2 18: irem 19: ifne 25 // comparatia cu 0 22: goto 38 25: iinc 2, 1 //j++ 28: goto 11 31: getstatic #84; //apelPrintStream 34: iload_1 35: invokevirtual #85; //PrintStream.println:(I)V 38: iinc 1, 1 // i++ 41: goto 2 44: return Java code/bytecodepentru JVM De ce nu sunt continue numerele/adresele de la bytecode? outer: for (int i = 2; i < 1000; i++) { for (int j = 2; j < i; j++) { if(i % j == 0) continue outer; } System.out.println(i); }

  14. Primeleincercari de abstractizare @echo off cls echoPressanykeyto start AProgram.exe! pause > nul AProgram.exe %1 iferrorlevel 1 gotoerror echoAProgramhasfinishedwhateverit wasdoing. gotoend error:echoSomethingwentwrongwithAprogram end PROGRAM EXEMPLU ! VERSION 0.0. CALL HELLO!apelareasubrutineiHELLO. CONTAINS !CONTAINS incheie program principal siincepedefinireasubrutinelor SUBROUTINE HELLO!definireacorp SUBROUTINA WRITE(*,*) "HELLO WORLD!“!afisez"HELLO WORLD!" la CONSOLA. END SUBROUTINE HELLO!SfarsitSUBROUTINA END PROGRAM EXEMPLU!sfarsit PROGRAM Fortran, primul limbaj de nivel înalt,

  15. Celemaicunoscutelimbaje din generatia a treia Functie de tipul de paradigmafolosit in rezolvareaproblemelor • Imperative: FORTRAN, COBOL, BASIC, C, Pascal • Functionale: Scheme, Lisp • LimbajeLogice: Prolog • Orientate obiect: • Orientate obiect pure:Java, Python • Orientate obiectsi imperative : C++, Perl, Visual Basic

  16. Limbaje din generatia a patra Acesteasuntdeja orientate peanumitetipuri de aplicatii SQLpentrubaze de date Limbajul Postscriptpentrudescriereauneipaginifolosit de imprimante PDFpentrudocumente on-line HTML and PHPpentrucontinutWorld Wide Web Mathematica

  17. Exemple - SQL Inserareaunui table intr-o baza de date: INSERT INTOangajati(id, Nume, Prenume, functie)VALUES (1445, ‘John’,’Smith',’manager’); Extragere de informatiifunctie de un criteriudintr-un tabel: SELECT id, Prenume, salariuFROMangajatiWHERE ( Job = ‘manager’ ); SQL esteconsiderat a fi declarativ

  18. Ceeste o paradigma de programare? • D1 (generală) Caz exemplar, model, prototip, situaţie ideală, structură tip, arhetip standard ş.a. • D2. (în filozofie, la L.Wittgenstein)Modelele filosofice, acele "tipare" care orientează gândirea noastră în direcţii predeterminate., • D3 (în filozofia limbajului) Listă de cazuri tipice de jocuri lingvistice prin care putem înţelege conceptul general..."

  19. Concepts, Techniques, andModels of Computer Programming (MIT Press, 2004)

  20. Paradigme de programare (wiki) Action Agent-oriented Aspect-oriented Automata-based Component-based Flow-based Pipelined Concatenative Concurrentcomputing Relativisticprogramming Data-driven Declarative (contrast: Imperative) Constraint Dataflow Cell-oriented (spreadsheets) Reactive Intensional Functional Logic Abductive logic Answer set Constraint logic Functional logic Inductive logic End-userprogramming Event-driven Service-oriented Time-driven Expression-oriented Feature-oriented Function-level (contrast: Value-level) Generic Imperative (contrast: Declarative) Procedural Language-oriented Discipline-specific Domain-specific Grammar-oriented Dialecting Intentional Metaprogramming Automatic Reflective Attribute-oriented Homoiconic Template Policy-based Non-structured (contrast: Structured) Array Nondeterministic Parallelcomputing Process-oriented Programming in the large andsmall Semantic Structured (contrast: Non-structured) Modular (contrast: Monolithic) Object-oriented (OOP) Byseparation of concerns: Aspect-oriented Role-oriented Subject-oriented Class-based Prototype-based Recursive Value-level(contrast: Function-level) Probabilistic

  21. Programarea nestructurată ASM .model small .stack 1024 . data z db? ; n MOV AX, @data MOV DS, AX MOV al, 3 ; m=3 ADD al,5 ; m=m+5 Jmpetl etl: MOVz,al ; n=5 MOV al,z MOV ah, 4ch INT 21h end start Basic 10 rem program exemplu 20 m=3 30 m=m+5 40 goto 50 50 n=5 60 m=n 60 end Bloc continuu Salt direct

  22. TIOBE Programming Community Index for August 2013 http://www.tiobe.com/content/paperinfo/tpci/index.html

  23. #include <stdio.h> intmain() { int a=1574, b=56, t, cmmdc; while(b != 0) { t = b; b = a % b; a = t; } cmmdc= a; printf("Greatestcommondivisior of %dand%d = %d\n", a, b, cmmdc); getch(); } CmmdcStructurat in C

  24. Procedural Java Script cmmdc function calculate() { var x = 167; var y = 3; var output; output = cmmdc(Math.abs(x), Math.abs(y)) } functioncmmdc(x, y) { while(y != 0) { var z = x % y; x = y; y = z; } returnx; }

  25. #include <stdio.h> int cmmdc(int u, int v) { if (v == 0) return u; else return cmmdc (v, u % v); } intmain(void) { int x =9, y=6; printf("The gcd of %d and %d is %d\n",x,y,cmmdc(x,y)); return 0; } Functional in C

  26. (define (cmmdcu v) (if (= v 0) u (cmmdcv (modulo u v) ) ) ) Functional cmmdc in Scheme Sintaxa Scheme pentru o functie: ( define ( function-name param1 param2 ... ) body of function definition )

  27. (define (euclid) (display "enter two integers:") (let ((u (read)) (v (read))) (display "the gcd of ") (display u) (display " and ") (display v) (display " is ") (display (gcd u v)) (newline) ) ) Functional cmmdc in Scheme

  28. public class oarescare{ private static long cmmdc(long u, long v) { long remainder; if (v < 0) v = -v; while ( v != 0 ) { remainder = u % v; u = v; v = remainder; } if ( u == 0 ) return 1; // cmmdc(0,x) = 1 else return (u>0)? u : -u; // modul } ... Restulclasei nu are importanta Imperativ in Java: cmmdc

  29. INTEGER FUNCTION IGCD(U,V) INTEGER U, V, TMP DO WHILE ( V .NE. 0 ) TMP = V V = MOD(U,V) U = TMP END DO IGCD = V RETURN END PROGRAM MAIN WRITE(6,*) "Input two integers:" READ(5,*) I, J WRITE(6,100) I, J, IGCD(I,J) 100 FORMAT("GCD of ",I4," and ",I4," is ",I4) STOP END Imperativoriginal:FORTRAN77

  30. public class CMMDC{ private final int value; public CMMDC( int value ) { this.value = value; } public int cmmdc ( int v ) { int u = value; while ( v != 0 ) { int t = u % v; u = v; v = t; } return u; } } Oop Java cmmdc

  31. cmmdc(U, V, U) :- V = 0. cmmdc(U, V, X) :- not (V = 0), Y is U mod V, gcd(V, Y, X). Cmmdc in programarelogica Prolog /* calculcmmdc(288,60) */ cmmdc(288, 60, X). consequence :- a, b, c.

  32. Concluzii Paradigmelesuntnecesare

  33. Join the club!

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