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Ada as a Language

Ada as a Language. Teaching. Ehud Lamm The Open University of Israel. Context. Current course: Software Engineering with Ada ( Booch ) . Good, but perhaps not good enough. Ada perceived as hindrance.

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Ada as a Language

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  1. Ada as a Language Teaching Ehud Lamm The Open University of Israel Ada-Europe’2003

  2. Context • Current course: Software Engineering with Ada (Booch). • Good, but perhaps not good enough. • Ada perceived as hindrance. • I examined several Java textbooks, and discovered Lisokv’s Program Development in Java. • What should be our next step? Ada-Europe’2003

  3. Why & How • Undergraduate SE course (CS students) • Classic Software Design • Traditional approach (imperative, OOP) • “Essentials of Software Engineering” • Modularity, Reliability, Readability, Flexibility, Software Life Cycle • University education Ada-Europe’2003

  4. Why & How • Practical course • Challenging design problems • Programming Should be Fun • Not just “getting it to work” • Students evaluate and re-evaluate their designs. • Make the language invisible Ada-Europe’2003

  5. Course Outline • Data Abstraction • ADT/ADO • Generic Units • Inheritance • Basic Tasking • Interface/Implementation • Adequacy • Operation Categories • Exceptions • Pre/Post Conditions • Invariants • Flexibility • Parameterization • Separate Compilation • Combining abstractions • Runtime Polymorphism • Heterogenic collections • Classwide/Dispatching • IS-A (LSP) • Composition (HAS-A) Ada-Europe’2003

  6. Q1: Log file Log  Gen_Log  Event’Class  Filter’Class Writer’Class  Dual Buffering Ada-Europe’2003

  7. Priority Queue Priority Queue Priority Queue Q2: Priority Queue Priority is priv. with func “<“(..) Priority is (<>) array of queues sorted linked list Ada-Europe’2003

  8. generic type Struct is lim. priv. type Elem is priv. with proc Insert with proc Remove … package Any_Struct is end; Struct is new Any_Struct(<>) Package Protect_Struct protected type Struct …. end; Ada-Europe’2003

  9. with pack Any_Iter(<>) function Max(S) … begin Start(S); while More_Elements(S) loop …. Next(S); end loop; End; pack BST --Binary_Search_Tree func BST.Max.. Ada-Europe’2003

  10. generic type Item is priv. packageSetsis type Set is abs. tagged null rec … end; generic with func “<“(I1,I2:Item); packageSets.Sorted_Listis type Set is new Sets.Set with priv. Ada-Europe’2003

  11. Does the choice of programming language really matter? Ada-Europe’2003

  12. No but... Ada-Europe’2003

  13. In theory, there’s no difference between theory and practice; In practice, there is. Ada-Europe’2003

  14. ‘Ideal’ Language Ada Java • Rich type system • Information hiding • Explicit interfaces • Value semantics • Genericity • Inheritance • Garbage collection • Design by Contract • First-class functions • Rich libraries, variety of tools Ada-Europe’2003

  15. Language Community • Libraries • Reusable code • Tools (e.g., VS IDEs, diagramming, DbC, etc.) • Tutorials/textbooks • etc. Ada-Europe’2003

  16. Problematic features (Ada)(in my experience) • Many kinds of Interfaces • Access to subprograms (accessibility) • Controlled (vs. other approaches to destructors/constructors) • Controlled & Generics • Controlling child visibility • Verbosity (exercises take too much time) Ada-Europe’2003

  17. Problematic features (Java) • Conjecture. Let me know what you think. • The type system • Reference semantics • Low level concurrency • Generics are coming.. Ada-Europe’2003

  18. The textbooks • A language can’t survive without good textbook, for all levels and needs. • Liskov’s book is much more suited for an academic SE course. Ada-Europe’2003

  19. Conclusions • Ada is still a strong candidate for a teaching language for SE • Most of the technical problems can be solved rather easily. • Better error messages should help with the remaining issues. • The language isn’t the problem: Good News and Bad News • Community and Cultural roadblocks Ada-Europe’2003

  20. Conclusions • Can we and should we try to change the way Ada is perceived in universities? • How? • Evangelism • Textbooks • GNAT • etc. Ada-Europe’2003

  21. Thank You Any Questions? Ada-Europe’2003

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