581362 Ohjelmointikielten periaatteet keväällä 2007: 4. harjoitukset 13.2.

22. [Modified from Scott's Review Questions for Chapter 8, Vihavainen] Answer the following questions concerning programming languages:
    1. What are the purposes of the stack pointer (sp) and the frame pointer (fp)? Why does a subroutine often need both? Why do compilers typically allocate space for arguments in the stack, even when they pass them in registers?
    2. Describe four common parameter-passing modes. How does a programmer choose which one to use when?
    3. How does an inline subroutine differ from a macro? How does a generic subroutine differ from a macro?
    4. Give examples in which it is useful to return a reference from a function (e.g., in C++).
    5. Why do you suppose that variable-length argument lists are so seldom supported by high-level programming languages?
    6. Describe the algorithm used to identify an appropriate handler when an exception is raised in a language (e.g., in Ada, C++ or Java). Explain why it is useful to define exceptions as classes in C++ and Java.
    7. Explain the difference between a coroutine and a subroutine. Explain the difference between a coroutine and a thread. What was the first high-level programming language to provide coroutines?

23. [Scott 8.1] Describe as many ways as you can in which functions in Algol-family programming languages differ from functions in mathematics.

24. 1. [Scott 8.2] Using your favorite language and compiler, write a program that determines the order in which subroutine parameters are evaluated.
    2. [Scott 8.11] Can you write a swap routine in Java, or in any other language with only call-by-sharing parameters? What exactly should swap do in such a language?

25. [Modified from Scott 8.6, Vihavainen, Wikla] Write (in a language of your choice or an appropriate pseudo-language) samples of procedures or functions that will have different effects, depending on whether arguments are passed by value, by reference, by value/result, or by name.
    Vihje: Nimiparametrivälityksen erilaisuutta voi havainnollistaa esimerkiksi taulukon alkion ja taulukon indeksin välittämisellä todellisina parametreina.

26. [Scott 8.28] Algol 60 allows labels to be passed as parameters, and allows gotos to these labels. One can imagine using these "nonlocal gotos" to escape from a nested function in response to unexpected conditions, but modern language designers regard label parameters as a bad idea. In what way(s) is the exception handling of Ada, Modula-3, or C++/Java/C# better?

27. [Modified from Scott's Review Questions for Chapter 9, Vihavainen] Answer the following questions concerning programming languages:
    1. What are generally considered to be the three defining characteristics of object-oriented programming?
    2. Explain why inline subroutines are particularly important in object-oriented programming languages.
    3. Why is object initialization simpler in a language with a reference model of variables (as opposed to a value model)?
    4. Explain the connection between dynamic method binding and (inclusion) polymorphism in object-oriented languages. Explain the difference between static and dynamic method binding (i.e., between virtual and nonvirtual methods and the ways to call them). Is a virtual method always bind at run time? Explain. Why does C++ use static method binding by default? Why do Smalltalk, Eiffel, and Java make all methods virtual, by default?

28. [Täydennetty Scott 9.1, Wikla] Some language designers argue that object orientation eliminates the need for nested subroutines. Do you agree? Why or why not? Sisäluokat toivat Javaan Algol-kieliperheen sisäkkäisten aliohjelmien kaltaisen näkyvyysrakenteen. Kannattiko? Hyötyjä? Haittoja?

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