Support abstract [LuaObject] classes

[ashtonmeuser]

The guard against abstract classes is, in my opinion, a little conservative. Users who desire an abstract parent class may simply drop abstract to appease Lua-CSharp, which is a worse compromise.

If I've overlooked a massive trap, please let me know.

[ashtonmeuser]

Perhaps this isn't necessary. The abstract parent class can simply omit [LuaObject] and add [LuaMember] all the same. A concrete child class with [LuaObject] will pick these up. For example:

public abstract partial class ParentClass
{
    [LuaMember("value")]
    public string Value { get; set; } = "";
}

[LuaObject]
public partial class ChildClass : ParentClass
{
    [LuaMember("number")]
    public int Number { get; set; }
}

ChildClass still has access to value.

[nuskey8]

This looks good, but are there any concerns? @akeit0

[akeit0]

LGTM!

[nuskey8]

It seems fine for abstract classes, but simply removing this check might cause code to be generated for interfaces as well. Wouldn't a proper check be necessary for this?

Sorry, that was a mistake. This is properly filtered at the SyntaxProvider stage.

[nuskey8]

Merged the PR. Thanks!