Difference between revisions of "VJET/Typing Object Literals and Function References"

Revision as of 18:34, 10 December 2012

JavaScript object literals provide a way to define and create new objects.  They are frequently used to define data structures and lightweight class instances.

Object Literals and Function Refs are frequently used constructs in JavaScript; they can be assigned to variables and properties, returned by functions, and passed as arguments.

In this example Point is comprised of two int properties, Line is comprised of two Point properties and the function SimpleLine takes two Point arguments.   We also define two function refs, createLine and isSingularity.

vjo.otype('Shape')
.defs ({
    Point: {
        x: undefined,    //< Number
        y: undefined    //< Number   },
    Line: {
        start: undefined,    //< Shape.Point
        end: undefined       //< Shape.Point
    },
 
    //> public Shape.Line createLine(Shape::Point pt1, Shape::Point pt2)
    createLine : vjo.NEEDS_IMPL,
 
    //> public boolean isSingularity(Shape.Line line)
    isSingularity: vjo.NEEDS_IMPL
 
})
.endType();

When you need to refer to an otype definition from another type you must:

Use the fully qualified name of the type, or use the .needs Comment, which serves as a shortcut to the otype namespace.

Do not include the otype in a .needs section; otypes are not true types, but are used to provide a namespace for custom types.

The following example:

Uses the needs Comment to create a shortcut for the otype namespace, samples.Shape.

Declares two Point properties and a Line property

Declares a function typed as SimpleLine

vjo.ctype('samples.ConstructShape')
//> needs samples.Shape
.protos({
    point1 : {x:0, y:0},     //< Shape::Point
    point2 : {x:10, y:0},     //< Shape::Point
    line1 : undefined,         //< Shape::Line
 
    //> public Shape.SimpleLine createLine()
    createLine : function(pt1, pt2) {
        this.line1 = {start: pt1, end: pt2} ;
    }
})
.endType();