# GodotOnReady

**GodotOnReady** is a [C# Source Generator] for Godot 3.x that adds convenient `onready`-like
features to your C# scripts in Godot Mono without any reflection.

* [`[OnReadyGet]`](#onreadyget) - Load a `Node` or `Resource` subclass into a
  field or property. Automatically exports a property so you can use the Godot
  editor to configure the path it loads.
* [`[OnReady]`](#OnReady) - Execute any 0-argument method during `_Ready`.

Bonus feature:

* [`[GenerateDataSelectorEnum]`](docs/GenerateDataSelectorEnum.md) - Generate an enum
  where each value is strongly associated with custom data.

## Prerequisites

* Godot 3.x, Mono version  
  <https://godotengine.org/download>  
  (4.0+ not supported due to C# source generator conflicts: [GodotOnReady#49](https://github.com/31/GodotOnReady/issues/49))

* .NET SDK 6.0 or greater  
  <https://dotnet.microsoft.com/download>

* Set Godot to use the `dotnet CLI` Build Tool  
  <details><summary>Screenshot showing this editor setting (click me!)</summary>

  ![](docs/img/EditorSettings-BuildTool-cli.png)

  </details>

## Project setup

Just add the [`GodotOnReady`](https://www.nuget.org/packages/GodotOnReady)
NuGet package to your project!

Your Godot project's `.csproj` file should look like this when you're done:

```xml
<Project Sdk="Godot.NET.Sdk/3.3.0">
  <PropertyGroup>
    <TargetFramework>net472</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="GodotOnReady" Version="1.2.4" />
  </ItemGroup>
</Project>
```

`GodotOnReady` includes two subpackages: a C# class library with a few attributes, and a source generator that detects when you use those attributes and generates code behind the scenes.

After clicking Build one time to set up the package, you may need to restart your IDE to let the generator load and provide autocomplete/intellisense information.

> For advanced alternatives like building from source or avoiding a reference to `GodotOnReady.Attributes`, see [/docs/advanced-setup.md](/docs/advanced-setup.md).

## Usage

### `[OnReadyGet]`

Instead of writing this repetitive code:

```cs
public class MyControl : Control
{
  [Export] public NodePath ButtonPath { get; set; }
  private Button _button;

  public override void _Ready()
  {
    _button = GetNode<Button>(ButtonPath);
  }
}
```

Write this code instead to do the same thing:

```cs
public partial class MyControl : Control
{
  [OnReadyGet] private Button _button;
}
```

The source generator figures out that the exported property should be called
`ButtonPath` by taking `_button`, trimming the leading `_` character, and
capitalizing the first letter.

The generated `_Ready()` method calls `base._Ready()` to support inheritance,
and includes some extra code to throw a more useful error message when the
`GetNode` fails.

The `[OnReadyGet]` source generator works for fields and properties. It also
works for `Resource` subclasses like `PackedScene` and `Texture`. You can also
use an `interface`, in which case GodotOnReady assumes the interface is
implemented by a node.

### `[OnReadyGet(...)]`

If you pass a string to the attribute, it's used as the node path to get. The
`[Export]` `ButtonPath` property isn't generated. This is useful if you know the
node will always be at a certain path, and avoids cluttering the Godot editor
with exported properties you'll never use:

```cs
[OnReadyGet("My/Button/Somewhere")] private Button _button;
```

If you know the node will usually be at one path, but someone may need to tweak
it in the Godot editor to point somewhere else, set `Export = true`. This sets
the string as the default path, and *also* exports `ButtonPath` for tweaking in
a scene:

```cs
[OnReadyGet("My/Button/Somewhere", Export = true)] private Button _button;
```

To get a node if it exists and ignore issues, pass `OrNull = true`. This means
GodotOnReady does nothing if the the path is `null`, empty, invalid, or points
at the wrong type of node. Normally, it throws an exception in these cases.

If you use `OrNull = true`, the `_button` member may be null, so be sure to
check before using it!

```cs
[OnReadyGet("My/Button/Maybe", OrNull = true)] private Button _button;
```

If your property is a `Resource` rather than a `Node`, pass a resource path
instead of a node path:

```cs
[OnReadyGet("res://icon.png")] private Texture _tex;
```

To get a property of a node instead of getting the node itself, specify
`Property = "..."`. GodotOnReady will cast the result for you, so this is
particularly useful for properties that aren't exposed in the statically-typed
Godot C# API.

For example, you can get an animation tree playback object without calling
`.Get("...")` and casting the result yourself:

```cs
[OnReadyGet("AnimationTree", Property = "parameters/playback")]
private AnimationNodeStateMachinePlayback _playback;
```

---

### `[OnReady]`

Using `OnReadyGet` causes GodotOnReady to generate a `public override void
_Ready()` method. This means you can't define `_Ready()` yourself. To run your
own code during `_Ready`, mark any number of zero-argument methods with
`[OnReady]`:

```cs
[OnReadyGet(OrNull = true)] private Button _button;
[OnReady] private void ConnectButtonOnReady()
{
  _button?.Connect("pressed", this, nameof(ButtonPressed));
}
```

The generated `_Ready()` method will then be:

```cs
public override void _Ready()
{
  base._Ready();
  if (ButtonPath != null) _button = GetNodeOrNull<global::Godot.Button>(ButtonPath);
  ConnectButtonOnReady();
}
```

### `[OnReady(...)]`

`OnReady` accepts one optional named argument, `Order`. This lets you change the order of `OnReady` method calls in `_Ready()`.

The calls in `_Ready()` are sorted by `Order`, from low to high. If two `OnReady` attributes have the same `Order` value (such as the default, `0`), the calls are sorted by the declaration order in the class file.

All `OnReadyGet` properties and fields are initialized before any `[OnReady(Order = 0)]` method is called.

For example, the following methods would normally be called from the top down (Two, One, Three), but `Order` makes them called in the order One, Two, Three:

```cs
[OnReady(Order = 2)] private void Two() => GD.Print("2");
[OnReady(Order = 1)] private void One() => GD.Print("1");
[OnReady(Order = 3)] private void Three() => GD.Print("3");
```

---

# Troubleshooting

### error CS0111: Type '***' already defines a member called '_Ready' with the same parameter types

This means your script contains `override void _Ready() { ... }`. Instead, use [`[OnReady]`](#OnReady) with a different method name, for example, `Ready`:

```cs
[OnReady] private void Ready() { ... }
```

This happens because GodotOnReady writes its own `public override void _Ready()`, and C# doesn't allow the same method to be overridden multiple times in the same class.

### error CS0260: Missing partial modifier on declaration of type '***'; another partial declaration of this type exists

Your class is most likely missing the `partial` modifier. The declaration
should look like this:

```cs
public partial class MyNode : Node
```

### I don't have a error message, but it isn't working!

* My variables are null even though they have `[OnReadyGet]` attributes!
* `[OnReady]` methods aren't being called!
* The `Path` properties don't show up in Godot!

If you hit one of those issues, it probably means the source generator didn't run.
Try these steps:

1. Hit the `Build` button at the top-right of the Godot editor to make sure your build is up to date.
1. Make sure you are using [.NET SDK version 5.0](#Prerequisites) or newer.
1. Make sure your [Build Tool is set to `dotnet CLI`](#Prerequisites).
1. Are you seeing a problem in a CI build, even though it works fine on your own machine? [Your CI may be using a Mono SDK](https://github.com/abarichello/godot-ci/issues/80). Make sure it's using the .NET SDK.

If none of that works, please file an issue. Include the output of
running `dotnet --info` on the command line, the Godot build log,
and if possible, the project.

# License

GodotOnReady is licensed under the [MIT license](LICENSE).


[C# Source Generator]: https://devblogs.microsoft.com/dotnet/new-c-source-generator-samples/