The ExtractEmmyLuaAPI utility command, invoked with `--emmy-lua-api`, produces a documentation file that is used by the [OpenRA Lua Language Extension](https://marketplace.visualstudio.com/items?itemName=openra.vscode-openra-lua) to provide documentation and type information is VSCode and VSCode compatible editors when editing the Lua scripts.
We improve the documentation and types produced by this utility in a few ways:
- Require descriptions to be provided for all items.
- Fix the type definitions of the base engine types (cpos, wpos, wangle, wdist, wvec, cvec) to match with the actual bindings on the C# side. Add some extra bindings for these types to increase their utility.
- Introduce ScriptEmmyTypeOverrideAttribute to allow the C# side of the bindings to provide a more specific type. The utility command now requires this to be used to avoid accidentally exporting poor type information.
- Fix a handful of scripts where the new type information revealed warnings.
The ability to ScriptEmmyTypeOverrideAttribute allows parameters and return types to provide a more specific type compared to the previous, weak, type definition. For example LuaValue mapped to `any`, LuaTable mapped to `table`, and LuaFunction mapped to `function`. These types are all non-specific. `any` can be anything, `table` is a table without known types for its keys or values, `function` is a function with an unknown signature.
Now, we can provide specific types. , e.g. instead of `table`, ReinforcementsGlobal.ReinforceWithTransport is able to specify `{ [1]: actor, [2]: actor[] }` - a table with keys 1 and 2, whose values are an actor, and a table of actors respectively. The callback functions in MapGlobal now have signatures, e.g. instead of `function` we have `fun(a: actor):boolean`. In UtilsGlobal, we also make use of generic types. These work in a similar fashion to generics in C#. These methods operate on collections, we can introduce a generic parameter named `T` for the type of the items in those collections. Now the return type and callback parameters can also use that generic type. This means the return type or callback functions operate on the same type as whatever type is in the collection you pass in. e.g. Utils.Do accepts a collection typed as `T[]` with a callback function invoked on each item typed as `fun(item: T)`. If you pass in actors, the callback operates on an actor. If you pass in strings, the callback operates on a string, etc.
Overall, these changes should result in an improved user experience for those editing OpenRA Lua scripts in a compatible IDE.
When making an Lua function call, any LuaCustomClrObject must be introspected via reflection in order to determine what to expose in Lua code. In OpenRA, we use these for any types that implement IScriptBindable, such as Actor.
Previously, we would need to pay the cost of this reflection for every individual Lua call an Actor used in its ScriptTriggers trait where it passed `self` as a parameter. This would be repeated every time. For performance, we now cache self.ToLuaValue in the trait and use that for all calls so we only pay the reflection cost once on trait construction. This removes a significant overhead in the Lua bridging code.
- Typo in documentation ("proximitry").
- Add spaces between sentences.
- Remove most occurrences of " " (two spaces) unless clearly used as indendation
- Punctuation (although no fullstop after filenames like "notifications.yaml").
If a class is caching the TraitsImplementing enumerable, instead cache the results of enumerating it to an array. The avoids having to enumerate the sequence each time it is needed.
