Defer in UnrealScript

In UnrealScript, there isn’t a direct equivalent to the defer keyword. However, we can simulate similar behavior using object-oriented programming principles and the CleanupGame event. Here’s how we might implement a similar concept:

class DeferExample extends Object;

var FileWriter FileHandle;

function Init()
{
    FileHandle = CreateFile("/Game/defer.txt");
    WriteFile(FileHandle);
}

function FileWriter CreateFile(string FilePath)
{
    local FileWriter NewFile;

    `log("Creating file");
    NewFile = new class'FileWriter';
    if (!NewFile.OpenFile(FilePath))
    {
        `warn("Failed to create file:" @ FilePath);
        return None;
    }
    return NewFile;
}

function WriteFile(FileWriter File)
{
    `log("Writing to file");
    File.Logf("data");
}

event CleanupGame()
{
    if (FileHandle != None)
    {
        `log("Closing file");
        FileHandle.CloseFile();
        FileHandle = None;
    }

    super.CleanupGame();
}

defaultproperties
{
}

In this UnrealScript example, we’re simulating the behavior of the defer keyword by using the CleanupGame event. This event is called when the game is shutting down, similar to how deferred functions in other languages are called at the end of their scope.

Here’s a breakdown of the code:

1. We define a DeferExample class that extends Object.

2. The Init function creates a file and writes to it. This is similar to the main function in the original example.

3. CreateFile and WriteFile functions are similar to their counterparts in the original example.

4. Instead of using defer, we implement the CleanupGame event. This event is called when the game is shutting down, ensuring that our file is properly closed.

5. In CleanupGame, we check if the FileHandle is not None (equivalent to nil in Go), and if so, we close the file.

To use this in an UnrealScript project, you would typically create an instance of this class when needed, call Init(), and the cleanup will happen automatically when the game shuts down.

It’s important to note that UnrealScript doesn’t have built-in file I/O operations like Go does. In a real UnrealScript project, you would likely use engine-specific methods for file operations or interface with the underlying C++ code.

This example demonstrates how to achieve similar functionality to the defer keyword in UnrealScript, even though the language doesn’t have an exact equivalent feature.