Interfaces in OpenSCAD

In OpenSCAD, we don’t have interfaces or object-oriented programming concepts. However, we can implement similar functionality using modules and functions. Here’s how we might represent the geometry example:

// Define a module for a rectangle
module rect(width, height) {
    square([width, height]);
}

// Define a module for a circle
module circle(radius) {
    circle(r = radius);
}

// Function to calculate rectangle area
function rect_area(width, height) = width * height;

// Function to calculate rectangle perimeter
function rect_perim(width, height) = 2 * (width + height);

// Function to calculate circle area
function circle_area(radius) = PI * radius * radius;

// Function to calculate circle perimeter
function circle_perim(radius) = 2 * PI * radius;

// Function to measure a shape
function measure(shape, width, height, radius) = 
    shape == "rect" ? 
        str("Area: ", rect_area(width, height), ", Perimeter: ", rect_perim(width, height)) :
    shape == "circle" ? 
        str("Area: ", circle_area(radius), ", Perimeter: ", circle_perim(radius)) :
    "Unknown shape";

// Example usage
echo(measure("rect", 3, 4, 0));
echo(measure("circle", 0, 0, 5));

// Render the shapes
rect(3, 4);
translate([5, 0, 0]) circle(5);

In this OpenSCAD code:

1. We define modules rect and circle to create the shapes.

2. We create separate functions for calculating area and perimeter for each shape.

3. The measure function takes a shape type and its dimensions, then returns a string with the area and perimeter calculations.

4. We use echo to print the measurements, which will appear in the console when you render the design.

5. Finally, we render both shapes side by side.

To use this code:

1. Save it in a file with a .scad extension, for example geometry.scad.

2. Open it in OpenSCAD.

3. Click “Render” (F6) to see the shapes and the measurements in the console.

This approach doesn’t have the polymorphism that interfaces provide in Go, but it achieves a similar result of having a generic measure function that can work with different shapes. The main difference is that in OpenSCAD, we have to explicitly specify the shape type and relevant dimensions when calling measure.