Defer in AngelScript

In AngelScript, there isn’t a direct equivalent to Go’s defer keyword. However, we can achieve similar functionality using try-finally blocks. Here’s how we can implement the same concept:

#include <angelscript.h>
#include <scriptbuilder/scriptbuilder.h>
#include <scriptstdstring/scriptstdstring.h>
#include <scriptfile/scriptfile.h>

void main()
{
    // Suppose we wanted to create a file, write to it,
    // and then close when we're done. Here's how we could
    // do that with a try-finally block.

    file f;
    try
    {
        f = createFile("/tmp/defer.txt");
        writeFile(f);
    }
    finally
    {
        // This will be executed at the end of the try block,
        // regardless of whether an exception was thrown or not.
        closeFile(f);
    }
}

file createFile(const string &in p)
{
    print("creating");
    file f;
    if (!f.open(p, "w"))
    {
        print("Failed to create file");
        exit();
    }
    return f;
}

void writeFile(file &f)
{
    print("writing");
    f.writeString("data\n");
}

void closeFile(file &f)
{
    print("closing");
    if (!f.close())
    {
        print("Failed to close file");
        exit();
    }
}

In this AngelScript version:

1. We use a try-finally block to ensure that the file is closed after we’re done with it, similar to Go’s defer.

2. The createFile function opens a file for writing and returns a file object.

3. The writeFile function writes data to the file.

4. The closeFile function closes the file and checks for errors.

5. We’ve used AngelScript’s built-in file type and its methods for file operations.

6. Error handling is done by checking the return values of file operations and using exit() to terminate the script in case of an error.

Running this script would produce output similar to:

creating
writing
closing

This example demonstrates how to ensure cleanup operations are performed in AngelScript, even if exceptions occur during file operations. While it’s not as concise as Go’s defer, it achieves the same goal of ensuring that resources are properly managed and cleaned up.