Defer in OpenSCAD

In OpenSCAD, there isn’t a direct equivalent to the defer keyword. However, we can achieve similar functionality using a combination of modules and function calls. Here’s how we might structure a similar example in OpenSCAD:

// Simulating file operations in OpenSCAD
file_path = "/tmp/defer.txt";

// Main module
module main() {
    file = create_file(file_path);
    write_file(file);
    close_file(file);
}

// Function to simulate file creation
function create_file(path) = 
    let(
        _ = echo("creating")
    ) path;

// Module to simulate writing to a file
module write_file(file) {
    echo("writing");
    // Simulating write operation
}

// Module to simulate closing a file
module close_file(file) {
    echo("closing");
    // Simulating close operation
}

// Call the main module
main();

In this OpenSCAD example, we’re simulating file operations since OpenSCAD doesn’t have built-in file handling capabilities like many general-purpose programming languages.

The main() module acts as our entry point. We create a “file” (which is just a string in this case), write to it, and then close it. These operations are simulated using separate functions and modules.

The create_file() function simulates file creation by echoing “creating” and returning the file path.

The write_file() module simulates writing to a file by echoing “writing”.

The close_file() module simulates closing a file by echoing “closing”.

While this doesn’t provide the same automatic cleanup functionality as the defer keyword in the original example, it does demonstrate a similar sequence of operations: create, write, and close.

To run this script in OpenSCAD, you would save it as a .scad file and open it in the OpenSCAD application. The console output would show:

ECHO: "creating"
ECHO: "writing"
ECHO: "closing"

This output confirms that our simulated file operations are executed in the correct order.

Note that OpenSCAD is primarily designed for creating 3D models, so this example is more of a conceptual translation rather than a practical use case in OpenSCAD. In real OpenSCAD scripts, you would typically be working with geometric shapes and transformations rather than file operations.