ITEC 380 2008fall ibarland

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lect08c
scope: closures

We saw three different variants on (static) scoping mechanisms last time. Scheme named them differently (let vs. let* vs. letrec), whereas Java uses let* for names of local variables and fields, and letrec for names of methods.

class Foo {
  //int b = 9;

  int foo( int a ) {
    // Try swapping these two next lines; not differing error message.
    a = b;
    int b;
    b = 5;
    
        
    //int c;
    for (int c = 0; c < 3; ++c ) {
        //int c;
        c = 9;
        }
         
    //return c;
    return -99;
    }

Implementing fields. Note that each (pair of) functions has its own closure.

Next time, we'll continue by thinking about how to (essentially) makes subclasses of this class rng.

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©2008, Ian Barland, Radford University Last modified 2008.Oct.29 (Wed)

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