Errors in OpenSCAD

Our first program will demonstrate error handling in OpenSCAD. Here’s the full source code:

// In OpenSCAD, we don't have built-in error handling mechanisms like in some other languages.
// Instead, we can use a combination of conditional statements and echo() for basic error handling.

function f(arg) = 
    arg == 42 ? [undef, "can't work with 42"] : 
    [arg + 3, undef];

function makeTea(arg) = 
    arg == 2 ? "no more tea available" :
    arg == 4 ? "can't boil water" :
    undef;

// Main program
for (i = [7, 42]) {
    result = f(i);
    if (result[1] != undef) {
        echo(str("f failed: ", result[1]));
    } else {
        echo(str("f worked: ", result[0]));
    }
}

for (i = [0:4]) {
    err = makeTea(i);
    if (err != undef) {
        if (err == "no more tea available") {
            echo("We should buy new tea!");
        } else if (err == "can't boil water") {
            echo("Now it is dark.");
        } else {
            echo(str("unknown error: ", err));
        }
    } else {
        echo("Tea is ready!");
    }
}

In OpenSCAD, we don’t have built-in error handling mechanisms like exceptions or error types. Instead, we use a combination of conditional statements and the echo() function to simulate error handling.

We define two functions, f() and makeTea(), which return arrays or strings to indicate success or failure. The first element of the array (or undef for strings) represents the successful result, while the second element (or the string itself) represents an error message.

In the main program, we use for loops to test these functions with different inputs. We check the return values to determine if an error occurred and echo appropriate messages.

To run this program, save it as a .scad file and open it in OpenSCAD. The console output will show the results:

ECHO: "f worked: 10"
ECHO: "f failed: can't work with 42"
ECHO: "Tea is ready!"
ECHO: "Tea is ready!"
ECHO: "We should buy new tea!"
ECHO: "Tea is ready!"
ECHO: "Now it is dark."

This example demonstrates how to implement basic error handling in OpenSCAD using conditional logic and return values. While it’s not as robust as error handling in some other languages, it provides a way to manage and respond to error conditions in your OpenSCAD scripts.