Today in CS362: Stack Frames and More

Admin
  Project, phase 1 graded
  Other homeworks not yet graded (sorry ...)
  Cool Enigma talks (extra credit)

Overview
  About project, phase 1
  Where we've been, where we're going
  Where do variables go?
    Stack
    Heap
  Stack Frames
  Non-Local Variables (maybe)

Project, Phase 1
  NO HAMMERS!
    Or .. try to choose the best tool for the job
    and be willing to switch tools.
  COMMENTS!
    (1) Use Javadoc
/**
 * Simple pithy sentence that describes the following thing.
 * More information, if appropriate (e.g. special cases).
 */

/**
 * This is a class comment.
 *
 * @author Joe Smith
 * @verson 1.0 of October 2002
 */

/** 
 * This is a method comment. 
 *
 * @throws HellFreezesOver
 *   when sam actually makes sense
 */
  (2) Explain each class, field, method, and constant.
  Particularly explain special values.

  (2a) Use the "six P's", if you're feeling particularly
  energetic.

  (3) Explain interesting parts of your code.

  (4) Optional: Explain steps of your code.

  (5) Somewhere give the "big picture"

  ENCAPSULATION!
    What should I reveal to the outside world?
    What should I reveal only to related classes?
    When is it appropriate to violate this?

/**
 * A StringTokenizer that keeps track of line numbers.
 */
public class HelpfulStreamTokenizer
  extends StreamTokenizer
{
  // +--------+-----------------------------------------
  // | Fields |
  // +--------+

  /** Current line number. */
  int lineno;

  // +--------------+-----------------------------------
  // | Constructors |
  // +--------------+

  public HelpfulStreamTokenizer(xxx)
  {
    super(xxx);
    lineno = 1;
  } // HelpfulStreamTokenizer(xxx)

  // +---------+----------------------------------------
  // | Methods |
  // +---------+

  /**
   * Get the next token.
   */
  public int nextToken() {
    int tok = super.nextToken();
    if (tok == StreamTokenizer.TT_EOL) ++lineno;
    return tok;
  } // nextToken()

  /**
   * Get the current line.  Wo hoo!
   */
  public int line() {
    return lineno;
  } // line()
} // class HelpfulStringTokenizer

  STYLE

methods

public whatever name(params) 
  throws A,B,C
{
}
public whatever name(params) {
}

conditionals
if (xxx) {
} 
else {
}
if (xxx) {
} else {
}
while {
}
try {
} catch {
}
try {
}
catch {
}
catch {
}
  ELEGANCE
    Try to write efficient code.
Convert between a keyword string and the corresponding 
integer constant.

  public String keyidToString(int keyid) {
    if (keyid < 0) 
      throw new YouAreABozoException();
    if (keyid > MAX_ID)
      throw new IAMABOZOException();
/*
    if (keyid == CONSTANT) return "constant";
    if (keyid == BEGIN) return "begin";
    ...
 */
/*
    switch (keyid)
      case CONSTANT: return "constant";
 */
 /*
   preliminary work
     String keywords[MAX_ID];
     keywords[CONSTANT] = "constant";
   later
     return keywords[keyid];
  }