Environment Variables in OpenSCAD

Environment variables are a universal mechanism for conveying configuration information to programs. Let’s look at how to set, get, and list environment variables in OpenSCAD.

// In OpenSCAD, we don't have built-in functions for environment variables.
// However, we can simulate this behavior using global variables.

// Simulating environment variables
FOO = "1";
BAR = "";

// Function to get environment variable (simulated)
function getenv(name) = 
    (name == "FOO") ? FOO :
    (name == "BAR") ? BAR :
    "";

// Function to set environment variable (simulated)
module setenv(name, value) {
    if (name == "FOO") FOO = value;
    if (name == "BAR") BAR = value;
}

// Main script
echo("FOO:", getenv("FOO"));
echo("BAR:", getenv("BAR"));

// Simulating listing all environment variables
echo("\nAll environment variables:");
echo("FOO");
echo("BAR");

In OpenSCAD, we don’t have direct access to system environment variables or built-in functions to manipulate them. Instead, we’ve simulated this behavior using global variables and custom functions.

To set a key/value pair, we use the setenv module (which modifies global variables in this simulation). To get a value for a key, we use the getenv function. This will return an empty string if the key isn’t present in our simulated environment.

We then print the values of our simulated environment variables.

In a real OpenSCAD environment, you would see output similar to this:

ECHO: "FOO:", "1"
ECHO: "BAR:", ""

ECHO: "All environment variables:"
ECHO: "FOO"
ECHO: "BAR"

Note that OpenSCAD doesn’t have a direct equivalent to os.Environ() for listing all environment variables. In a real-world scenario, you might need to use external tools or scripts to interact with actual system environment variables when working with OpenSCAD.

This example demonstrates how you might simulate environment variable-like behavior within OpenSCAD, but keep in mind that for actual system interaction, you may need to use OpenSCAD in conjunction with other tools or scripts.