Reading Files in OpenSCAD

Here’s the translation of the Go code for reading files into OpenSCAD, along with explanations:

Reading and writing files are basic tasks needed for many OpenSCAD programs. First we’ll look at some examples of reading files.

// Helper function to check for errors
function check(result) = 
    result == undef ? assert(false, "Error occurred") : result;

// Read entire file contents
function read_file(filename) =
    check(import(filename, "raw"));

// Read specific lines from a file
function read_lines(filename, start_line, num_lines) =
    [for (i = [start_line : start_line + num_lines - 1]) 
        check(import(str(filename, ":", i, ":", i), "raw"))];

// Main function
function main() =
    let(
        // Read entire file
        dat = read_file("/tmp/dat"),
        _ = echo(dat),

        // Read specific lines
        lines = read_lines("/tmp/dat", 0, 2),
        _ = echo(str("First two lines: ", lines[0], ", ", lines[1]))
    ) 0;

main();

In OpenSCAD, file operations are more limited compared to Go. We use the import() function to read files, which is primarily designed for importing 3D models but can also be used to read text files.

The read_file() function reads an entire file into memory, similar to os.ReadFile() in Go.

The read_lines() function allows reading specific lines from a file. This is somewhat analogous to seeking and reading in Go, although less flexible.

Note that OpenSCAD doesn’t have direct equivalents for concepts like file descriptors, seeking, or buffered reading. Instead, we focus on reading entire files or specific lines.

To use this script:

1. Create a file named /tmp/dat with some content.
2. Run the OpenSCAD script.

The script will output the entire file content and then the first two lines of the file.

OpenSCAD’s file reading capabilities are more limited compared to Go’s, but these functions provide basic file reading functionality suitable for many OpenSCAD use cases.