Workbench Elements

A workbench in general consists of the following elements:

• A leading keyword: part, sketch, or op,
• an identifier that names the workbench,
• a building plan defined by a parameter list following the identifier,
• optional initialization code, which is placed and executed before any initializer,
• optional initializers, offering alternative ways to initialize the building plan,
• optional functions, acting as local subroutines with their own parameters and code bodies,
• optional properties, accessible from outside and set from the inside,
• and typically some building code, which runs after all initialization steps and generates the final objects.

The following code demonstrates (on the basis of a sketch) most of these elements which we will discuss in the following pages in detail.

// Sketch with a `radius` as building plan.
// Which will automatically become a property.
sketch Wheel(radius: Length) {
    // Initialization code...
    const FACTOR = 2;

    // Initializer #1
    init(diameter: Length) {
        // must set `radius`
        radius = diameter / FACTOR;
    }

    // No code in between!

    // Initializer #2
    init(r: Length) {
        // must set `radius`
        radius = r;
    }

    // Function (sub routine)
    fn into_diameter(r: Length) {
        return r * FACTOR;
    }

    // Building code...

    // Set a property which can be seen from outside.
    prop diameter = into_diameter(radius);

    // Local variable `r`
    r = radius;

    // Create a circle.
    std::geo2d::Circle(r);
}

use std::debug::*;

// Call sketch with diameter.
d = Wheel(diameter = 2cm);
// Check radius property.
assert_eq([d.radius, 1cm]);

// Call sketch with radius.
r = Wheel(radius = 2cm);
// Check diameter property.
assert_eq([r.diameter, 4cm]);

r - d;

Output :