282bd37e5c
We aim to make the C# API reflection-free, mainly for concerns about
performance, and to be able to target NativeAOT in refletion-free mode,
which reduces the binary size.
One of the main usages of reflection still left was the dynamic
invokation of callable delegates, and for some time I wasn't sure
I would find an alternative solution that I'd be happy with.
The new solution uses trampoline functions to invoke the delegates:
```
static void Trampoline(object delegateObj, NativeVariantPtrArgs args, out godot_variant ret)
{
if (args.Count != 1)
throw new ArgumentException($"Callable expected 1 arguments but received {args.Count}.");
string res = ((Func<int, string>)delegateObj)(
VariantConversionCallbacks.GetToManagedCallback<int>()(args[0])
);
ret = VariantConversionCallbacks.GetToVariantCallback<string>()(res);
}
Callable.CreateWithUnsafeTrampoline((int num) => "Foo" + num, &Trampoline);
```
Of course, this is too much boilerplate for user code. To improve this,
the `Callable.From` methods were added. These are overloads that take
`Action` and `Func` delegates, which covers the most common use cases:
lambdas and method groups:
```
// Lambda
Callable.From((int num) => "Foo" + num);
// Method group
string AppendNum(int num) => "Foo" + num;
Callable.From(AppendNum);
```
Unfortunately, due to limitations in the C# language, implicit
conversions from delegates to `Callable` are not supported.
`Callable.From` does not support custom delegates. These should be
uncommon, but the Godot C# API actually uses them for event signals.
As such, the bindings generator was updated to generate trampoline
functions for event signals. It was also optimized to use `Action`
instead of a custom delegate for parameterless signals, which removes
the need for the trampoline functions for those signals.
The change to reflection-free invokation removes one of the last needs
for `ConvertVariantToManagedObjectOfType`. The only remaining usage is
from calling script constructors with parameters from the engine
(`CreateManagedForGodotObjectScriptInstance`). Once that one is made
reflection-free, `ConvertVariantToManagedObjectOfType` can be removed.
|
||
|---|---|---|
| .. | ||
| build_scripts | ||
| doc_classes | ||
| editor | ||
| glue | ||
| icons | ||
| mono_gd | ||
| thirdparty | ||
| utils | ||
| __init__.py | ||
| .editorconfig | ||
| .gitignore | ||
| class_db_api_json.cpp | ||
| class_db_api_json.h | ||
| config.py | ||
| csharp_script.cpp | ||
| csharp_script.h | ||
| Directory.Build.props | ||
| Directory.Build.targets | ||
| godotsharp_defs.h | ||
| godotsharp_dirs.cpp | ||
| godotsharp_dirs.h | ||
| interop_types.h | ||
| managed_callable.cpp | ||
| managed_callable.h | ||
| mono_gc_handle.cpp | ||
| mono_gc_handle.h | ||
| README.md | ||
| register_types.cpp | ||
| register_types.h | ||
| SCsub | ||
| signal_awaiter_utils.cpp | ||
| signal_awaiter_utils.h | ||
How to build and run
- Build Godot with the module enabled:
module_mono_enabled=yes. - After building Godot, use it to generate the C# glue code:
<godot_binary> --generate-mono-glue ./modules/mono/glue - Build the C# solutions:
./modules/mono/build_scripts/build_assemblies.py --godot-output-dir ./bin
The paths specified in these examples assume the command is being run from the Godot source root.
How to deal with NuGet packages
We distribute the API assemblies, our source generators, and our custom MSBuild project SDK as NuGet packages. This is all transparent to the user, but it can make things complicated during development.
In order to use Godot with a development of those packages, we must create a local NuGet source where MSBuild can find them. This can be done with the .NET CLI:
dotnet nuget add source ~/MyLocalNugetSource --name MyLocalNugetSource
The Godot NuGet packages must be added to that local source. Additionally, we must make sure there are no other versions of the package in the NuGet cache, as MSBuild may pick one of those instead.
In order to simplify this process, the build_assemblies.py script provides
the following --push-nupkgs-local option:
./modules/mono/build_scripts/build_assemblies.py --godot-output-dir ./bin \
--push-nupkgs-local ~/MyLocalNugetSource
This option ensures the packages will be added to the specified local NuGet source and that conflicting versions of the package are removed from the NuGet cache. It's recommended to always use this option when building the C# solutions during development to avoid mistakes.
Double Precision Support (REAL_T_IS_DOUBLE)
Follow the above instructions but build Godot with the float=64 argument to scons
When building the NuGet packages, specify --float=64 - for example:
./modules/mono/build_scripts/build_assemblies.py --godot-output-dir ./bin \
--push-nupkgs-local ~/MyLocalNugetSource --float=64