Concepts of Programming Languages ---- Chapter 9 Subprograms

Concepts of Programming Languages ---- Chapter 9 Subprograms

Name : Fandy Limardi
NIM : 1601210713
Lecture : Tri Djoko Wahjono, Ir., M.Sc. (D0206)
Assignment : Concept of programming languages ---- Chapter 9 Subprograms

Review Questions

1.   What are the three general characteristics of subprograms?

       ·         each subprogram has a single entry point

       ·         the calling program unit is suspended during the execution of the called subprogram

       ·         control always returns to the caller when the subprogram execution terminates

2.   What does it mean for a subprogram to be active?

A subprogram is said to be active after having been called, it has begun execution but has not yet completed that execution.

6.   What is ruby array formal parameter?

ruby array formal parameter is the single parameter which followed by the hash item which preceded by an asterik. Ruby allows a variable number of parameters in a way similar to C# because ruby arrays can store different types.

7.   What is a parameter profile?  what is a subprogram protocol?

      Parameter profile is a subprogram contains the number, order , and types of its formal 
      parameters. Subprogram protocol is a subprogram which its parameter profile plus, if it is a  
      function , its return type. In languages in which subprogram have types, those types are 
      defined by the subprogram's protocol.

11. What are the design issues for subprograms?

       ·         are local variables statically or dynamically allocated?

       ·         can subprogram definitions appear in other subprogram definitions?

       ·         what parameter-passing method or methods are used?

       ·         are the types of the actual parameters checked against the types of the formal parameters?

       ·         if a subprograms can be passed as parameters and subprograms can be nested, what is the    
       referencing environment of a passed subprogram?

       ·          can subprograms be overloaded?

       ·          can subprograms be generic?

       ·         if the language allows nested subprograms , are closures supported?

12. What are the advantages and disadvantages of dynamic local variables?

Advantages

       ·         being flexibility they provide to the subprogram

       ·         the storage for local variables in an active subprogram can be shared with the local 
      variables in all inactive subprograms.

Disadvantages

       ·         there is the cost of time required to allocate, initialize and deallocate such variables for each 
       call to the subprogram.

       ·         accesses to stack- dynamic local variables must be indirect.

       ·         when all local variables are stack dynamic, subprograms cannot be history sensitive.

24. What is an overloaded subprogram?

Overloaded subprogram is a subprogram that has the same name as another subprogram in the same referencing environment

25. What is ad hoc binding?

Ad hoc binding is the environment of the call statement that passed the subprogram as an actual parameter

26. What is multicast delegate?

Multicast delegate is all of the methods stored in a delegate instance are called in the order in which they were placed in the instance.

Problem Set

3.   Argue in support of the template functions of C++. How is it different from the template functions in other languages?

      C++ templated classes are instantiated to become typed classes at compile time. For example, an instance of the templated Stack class, as well as an instance of the typed class, can be created with the following declaration: Stack<int> myIntStack; However, if an instance of the templated Stack class has already been created for the int type, the typed class need not be created.

4.   Suppose you want to write a method that prints a heading on a new output page, along with a page number that is 1 in the first activation and that increases by 1 with each subsequent activation. Can this be done without parameters and without reference to nonlocal variables in Java? Can it be done in C#?

      This can be done in both Java and C#, using a static (or class) data member for the page number.

11. Compare the use of closures by programming languages.

Nearly all functional programming languages, most scripting languages, and at least one primarily imperative language, C#, support closures. These languages are static-scoped, allow nested subprograms, and allow subprograms to be passed as parameters.

12. Research Jensen’s Device, which was a widely known use of pass-by-name parameters, and write a short description of what it is and how it can be used.

      Implementing a pass-by-name parameter requires a subprogram to be passed to the called subprogram to evaluate the address or value of the formal parameter. The referencing environment of the passed subprogram must also be passed. This subprogram/referencing environment is a closure. Pass-by-name parameters are both complex to implement and inefficient. They also add significant complexity to the program, thereby lowering its readability and reliability. Because pass-by-name is not part of any widely used language, it is not discussed further here. However, it is used at compile time by the macros in assembly languages and for the generic parameters of the generic subprograms in C++, Java 5.0, and C# 2005.

15. How is the problem of passing multidimensional arrays handled by Ada?

Ada compilers are able to determine the defined size of the dimensions of all arrays that are used as parameters at the time subprograms are compiled.