[tiscript] ‘this’ and ‘this super’ function arguments

Each function in JavaScript and TIScript gets implicit argument named this.

So when you call method of some object as foo.bar(1) then foo object is passed to the bar(param) function as a value of this argument. And the param will get value of 1.

All of us who are practicing JS, Python, Ruby, etc. know about that ‘this’ thing pretty well.

But what shall you do when you have inner function and want to access ‘this’ value of outer function? The only way in JavaScript for that is to declare other variable with distinct name and assign ‘this’ to it: var that = this;.

To cover such code patterns I’ve introduced in TIScript “super this” concept, so we have following implicit variables in any function:

  • this – standard this variable;
  • this super – standard this variable of outer function;
  • this super super – this variable of outer-outer function;
  • etc.

Here is an example that outputs “6” in standard output:

class Test {

  function this(data) { // constructor
    this.data = data;   // instance field 
  }

  function Outer(arg1) {
    // this - hidden argument, local variable 
    // arg1 - argument, local variable

    function Inner(arg2)  {
      // this - hidden argument, local variable 
      // arg2 - argument, local variable
      // arg1 - outer variable - outer argument
      // this super - outer variable - outer 'this' argument
      
      return 
        (this super).data   // 1 
        + arg1              // 2
        + arg2              // 3
    }
    return Inner;
  }
}

var test = new Test(1);

var innerFunc = test.Outer(2);

stdout.println( innerFunc(3) );

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