Code Generator generates invalid code for components whose names are C# keywords

[akanix42]

Only recently started using Entitas, gotta say it's really awesome!
I just ran into this issue while setting up some components:

Create a BaseComponent:

using Entitas;

[Game]
public sealed class BaseComponent : IComponent
{
  public string value;
}

Run the Generate command in Unity.

The generated code has errors because base is a keyword in C#. My key takeaway is to just note that you can't use keywords as your component names (which of course makes sense, since you can't use keywords as variable names). However, it would be nice if the generator displayed a friendly error instead of generating invalid code.

The error message is:

Assets/Sources/Generated/Game/Components/GameBaseComponent.cs(11,29): error CS1519: 
Unexpected symbol `base' in class, struct, or interface member declaration

Here's the generated code, for reference:

//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by Entitas.CodeGeneration.Plugins.ComponentEntityApiGenerator.
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
public partial class GameEntity {

    public BaseComponent base { get { return (BaseComponent)GetComponent(GameComponentsLookup.Base); } }
    public bool hasBase { get { return HasComponent(GameComponentsLookup.Base); } }

    public void AddBase(string newValue) {
        var index = GameComponentsLookup.Base;
        var component = CreateComponent<BaseComponent>(index);
        component.value = newValue;
        AddComponent(index, component);
    }

    public void ReplaceBase(string newValue) {
        var index = GameComponentsLookup.Base;
        var component = CreateComponent<BaseComponent>(index);
        component.value = newValue;
        ReplaceComponent(index, component);
    }

    public void RemoveBase() {
        RemoveComponent(GameComponentsLookup.Base);
    }
}

//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by Entitas.CodeGeneration.Plugins.ComponentMatcherApiGenerator.
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
public sealed partial class GameMatcher {

    static Entitas.IMatcher<GameEntity> _matcherBase;

    public static Entitas.IMatcher<GameEntity> Base {
        get {
            if (_matcherBase == null) {
                var matcher = (Entitas.Matcher<GameEntity>)Entitas.Matcher<GameEntity>.AllOf(GameComponentsLookup.Base);
                matcher.componentNames = GameComponentsLookup.componentNames;
                _matcherBase = matcher;
            }

            return _matcherBase;
        }
    }
}

[rglobig]

Would be possible if the generator generates it like this:

public BaseComponent @base { get { return (BaseComponent)GetComponent(GameComponentsLookup.Base); } }

The @ symbol allows to use reserved words.

[roygear]

I implemented such "@" fashion to generator, but I don't like it.

The interface like this:
entity.@base.value = "odd";

or add "_"
entity._base.value = "odd2";

[sschmid]

My suggestion is not to use reserved keywords

I'm a bit curious here. if you use a field with @ like int @int you can access it like object.int and not object.@int.

The API would stay the same but we could use component names like FloatComponent, BaseComponent and EventComponent. I can think of the following solution: the code generator has an array of all reserved keywords (https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/) and if the naming matches one of these it writes it with an @.

[roygear]

I never used @ for field name, not sure any potential problem with it.

So, here is implementation which adding "_" in front of keyword.

Usage:

public sealed class BaseComponent : IComponent
{
    public string value;
}

	...
	
	var e = contexts.game.CreateEntity();

	e.AddBase("Add");
	e.ReplaceBase("For ReactiveSystem");
	e.RemoveBase();

	e._base.value = "For critical code";

This DLL based on Entitas 1.7, tested in Roslyn version

Entitas.CodeGeneration.Plugins.dll.zip

[roygear]

if you like to try the @ version
Entitas.CodeGeneration.Plugins_at.dll.zip

[sschmid]

Feel free to create a pull request with this implementation, see we all can enjoy components with reserved keywords :)

[roygear]

which version? "_" or "@" ?

[PythagoRascal]

Personally, I'd say "@" because "_" is often used for private variables and at first glance that might be confusing.

[roygear]

PR submitted using "@" version

[sschmid]

ref #756