Lua scripting environment

[philpax]

Description

There are a fair few suggestions in this very repo that don't really require a full Dalamud plugin, but would still be nice to have around. I propose a sandboxed Lua environment where users can write and edit scripts that have access to a subset of Dalamud's functionality; these scripts can then be gzip-b64'd and shared on the Discord, or included by default in the Lua scripting plugin itself.

More info

Some general thoughts:

• This would encourage users to paste in code from Discord, which is a potential minefield. That's why I would ideally want to sandbox it so that you can't do anything naughty:
  • No arbitrary IO access. Maybe access to a single file handle to save/load data.
  • No access to plugin IPC or configuration.
  • No access to the wider .NET ecosystem, unless explicitly provided. You would get access to everything Dalamud provides, but you're not getting access to System.
  • No access to any of the Lua functions that let you do bad things (no script evaluation, no OS interaction functions, etc)
• An in-game text editor would be great (you can pretend it's 2009 and you're writing Expression 2 scripts for GMod). Best bet would be https://github.com/BalazsJako/ImGuiColorTextEdit or one of its many forks, but you'd have to bind it to C# somehow. I see C++/CLI in the future.
• Each script gets its own Lua VM so they don't interfere with each other. One script = one file for now (if you're going past one file, you should probably write an actual plugin)
• General interface: you have a list of scripts that you can toggle on and off. You can create a script or import/export a script (gzip-b64). You can also open the directory the scripts are stored in.
  • could be worth having some comment metadata at the top to provide information about the author and where you can ask for help
• xlua is the best Lua interface for C#, but it appears you can't really use it outside of Unity. Would have to use nlua instead, which means no generics (as far as I can tell)

Here are some suggestions that I think could be handled by this:

• 462 / #493

• 7

• 562

• 540 (with a sound playing API)

• 532

• 502

• and probably plenty more, I just had a look at the first few pages

This could be used as a potential replacement for the Scratchpad, but the Scratchpad would not be as sandboxed, so it'd still be worth keeping around for its current users.

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• [x] I checked if this request wasn't already proposed
• [x] I made sure this request follows Dalamud's plugin guidelines

[philpax]

If this is something people are interested in, I might have a go at it at some point.

[philpax]

Just making a note here for posterity: I ended up implementing this by loading C# scripts - similar to Goatscript Classic:tm: - and it works, but I haven't submitted to testing/release because it needs significant sandboxing. It can be found here.

These are the rough notes I made about what needs to be done next:

• metadata json at the top of the file
• try class-wrapping (not sure how this will work with top-level statements)
• rework UI to be less messy
• handle errors with falloff (up to five errors before the script is automatically disabled)
• direct as many errors to message boxes as possible
• think of a new name?
• add more helper methods
• add copy to clipboard button
• make editing the file and then hitting reload not wipe out your changes
• take inspiration from s&box: https://wiki.facepunch.com/sbox/AccessList