Upgrade to Pro — share decks privately, control downloads, hide ads and more …

CSE564 Lecture 02

CSE564 Lecture 02

Software Design
The Beginning
(202101)

B546a9b97d993392e4b22b74b99b91fe?s=128

Javier Gonzalez

September 02, 2020
Tweet

Transcript

  1. jgs CSE 564 Software Design Lecture 02: The Beginning Dr.

    Javier Gonzalez-Sanchez javiergs@asu.edu javiergs.engineering.asu.edu | javiergs.com PERALTA 230U Office Hours: By appointment
  2. jgs Previously

  3. jgs 00000010 What Makes a Good Design? OOAD, Grady Booch,

    2007
  4. jgs The Beginning

  5. jgs 00000010 Timeline 1971 1985 1972 1969 1959 1995 1997

  6. jgs 00000010 Stepwise Refinement (1971) Program Development by Stepwise Refinement

    Niklaus Wirth Communications of the ACM April 1971 Computer Scientist, Turing Award 1984 for developing a sequence of innovative programming languages.
  7. jgs 00000010 Stepwise Refinement (1971) Note: The author gratefully acknowledges

    the helpful and stimulating influence of many discussions with • A. Hoare - sorting algorithm quicksort (1959) • E. W. Dijkstra - shortest path algorithm (1956) and compiler construction, operating systems, distributed systems, concurrent programming, programming language, program verification, graph algorithms, etc.
  8. jgs 00000010 Stepwise Refinement (1971) Key Idea: Decoupling Specifically, This

    is ONE (of many) approach to achieve Decoupling Definition: Decoupling is separate, disengage, or dissociate (something) from something else. What is the something in this case?
  9. jgs 00000010 Stepwise Refinement (1971) • Top-Down Design Technique •

    It is about successive refinement Definition: Refinement = task is broken up into a number of subtasks What is a Task? Goals: • Refinement implies design decisions based upon a set of design criteria. • Among these criteria are efficiency, storage economy, clarity, and regularity of structure (quality). • maintainability and extensibility (portability) can be measured primarily in terms of the degree to which a program is neatly structured.
  10. jgs 00000010 Stepwise Refinement (1971) Author’s Conclusions: • programming is

    not about learning a powerful programming language • programming is NOT easy • Students must be taught to be conscious of the involved decisions and to critically examine and to reject solutions, sometimes even if they are correct as far as the result is concerned; they must learn to weigh the various aspects of design alternatives in the light of these criteria.
  11. jgs 00000010 Stepwise Refinement (1971) Author’s Conclusions: • Programming =

    Coding + Design • Function-driven development • Function, method, procedure • Thought Processes: Sequence, Selection, Iteration
  12. jgs And …

  13. jgs 00000010 Timeline 2021

  14. jgs 00000010 Questions § Who many words in an abstract?

    § Who many lines in a paragraph? § Who many paragraphs in a chapter? § Who many pages in a chapter? § Who many chapters in a book?
  15. jgs 00000010 Questions § How many LOC in a function

    or procedure or method? § What about complexity (Cyclomatic Complexity) ? § How many inputs? § How many outputs? § What about exception handling?
  16. jgs Case Study Stepwise Refinement Decision-making

  17. jgs 00000010 [ - < < ( - ) >

    > ] [ ( < - > ) ] main () { home if(){ if(){ while() { whatever } } } } home () { while() { if() { something } } } Case Study
  18. jgs 00000010 Homework § You won’t submit yet § Draft

    the source code. It will be discussed in our next lecture Problem to solve: 1. Read a file line by line 2. Split lines in words (group of characters) 3. Classify each word as: name, keyword (if, while), or delimiter (parenthesis and curly brackets) 4. Store them in a data structure
  19. jgs 00000010 Homework Read: § On the Criteria To Be

    Used in Decomposing Systems into Modules D.L. Parnas Communications of the ACM April 1972
  20. jgs 00000010 To be continued …

  21. jgs CSE 564 Software Design Javier Gonzalez-Sanchez javiergs@asu.edu Spring 2021

    Disclaimer. These slides can only be used as study material for the class CSE564 at ASU. They cannot be distributed or used for another purpose.