Integrate connect/emit with Rust named function pointers

Author: Bromeon

godot-core/src/builtin/mod.rs

@@ -63,8 +63,6 @@ pub mod __prelude_reexport {
     pub use string::{GString, NodePath, StringName};
     pub use transform2d::*;
     pub use transform3d::*;
-    // TODO move to register?
-    pub use typed_signal::{Func, TypedSignal};
     pub use variant::*;
     pub use vectors::*;
 
@@ -113,7 +111,6 @@ mod signal;
 mod string;
 mod transform2d;
 mod transform3d;
-mod typed_signal;
 mod variant;
 mod vectors;
 

godot-core/src/classes/class_runtime.rs

@@ -47,7 +47,7 @@ pub(crate) fn display_string<T: GodotClass>(
     obj: &Gd<T>,
     f: &mut std::fmt::Formatter<'_>,
 ) -> std::fmt::Result {
-    let string: GString = obj.raw.as_object().to_string();
+    let string: GString = obj.raw.as_object_ref().to_string();
     <GString as std::fmt::Display>::fmt(&string, f)
 }
 

godot-core/src/obj/gd.rs

@@ -327,6 +327,11 @@ impl<T: GodotClass> Gd<T> {
             .expect("Upcast to Object failed. This is a bug; please report it.")
     }
 
+    /// Equivalent to [`upcast_mut::<Object>()`][Self::upcast_mut], but without bounds.
+    pub(crate) fn upcast_object_mut(&mut self) -> &mut classes::Object {
+        self.raw.as_object_mut()
+    }
+
     /// **Upcast shared-ref:** access this object as a shared reference to a base class.
     ///
     /// This is semantically equivalent to multiple applications of [`Self::deref()`]. Not really useful on its own, but combined with

godot-core/src/obj/raw_gd.rs

@@ -207,11 +207,16 @@ impl<T: GodotClass> RawGd<T> {
     //     self.as_target_mut()
     // }
 
-    pub(crate) fn as_object(&self) -> &classes::Object {
+    pub(crate) fn as_object_ref(&self) -> &classes::Object {
         // SAFETY: Object is always a valid upcast target.
         unsafe { self.as_upcast_ref() }
     }
 
+    pub(crate) fn as_object_mut(&mut self) -> &mut classes::Object {
+        // SAFETY: Object is always a valid upcast target.
+        unsafe { self.as_upcast_mut() }
+    }
+
     /// # Panics
     /// If this `RawGd` is null. In Debug mode, sanity checks (valid upcast, ID comparisons) can also lead to panics.
     ///

godot-core/src/private.rs

@@ -17,11 +17,9 @@ pub use sys::out;
 #[cfg(feature = "trace")]
 pub use crate::meta::trace;
 
-use crate::builtin::Variant;
 use crate::global::godot_error;
 use crate::meta::error::CallError;
 use crate::meta::CallContext;
-use crate::obj::{bounds, BaseMut, GodotClass, Inherits};
 use crate::sys;
 use std::sync::atomic;
 #[cfg(debug_assertions)]

godot-core/src/registry/as_func.rs

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) godot-rust; Bromeon and contributors.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+// https://geo-ant.github.io/blog/2021/rust-traits-and-variadic-functions
+//
+// Could be generalized with R return type, and not special-casing `self`. But keep simple until actually needed.
+
+pub trait AsFunc<I, Ps> {
+    fn call(&mut self, maybe_instance: I, params: Ps);
+}
+
+// pub trait AsMethod<C, Ps> {
+//     fn call(&mut self, instance: &mut C, params: Ps);
+// }
+
+// Now generalize via macro:
+macro_rules! impl_signal_recipient {
+    ($( $args:ident : $Ps:ident ),*) => {
+        // Global and associated functions.
+        impl<F, R, $($Ps,)*> AsFunc<(), ( $($Ps,)* )> for F
+            where F: FnMut( $($Ps,)* ) -> R
+        {
+            fn call(&mut self, _no_instance: (), ($($args,)*): ( $($Ps,)* )) {
+                self($($args,)*);
+            }
+        }
+
+        // Methods.
+        impl<F, R, C, $($Ps,)*> AsFunc<&mut C, ( $($Ps,)* )> for F
+            where F: FnMut( &mut C, $($Ps,)* ) -> R
+        {
+            fn call(&mut self, instance: &mut C, ($($args,)*): ( $($Ps,)* )) {
+                self(instance, $($args,)*);
+            }
+        }
+    };
+}
+
+impl_signal_recipient!();
+impl_signal_recipient!(arg0: P0);
+impl_signal_recipient!(arg0: P0, arg1: P1);
+impl_signal_recipient!(arg0: P0, arg1: P1, arg2: P2);

godot-core/src/registry/mod.rs

@@ -8,12 +8,14 @@
 // Note: final re-exports from godot-core are in lib.rs, mod register::private.
 // These are public here for simplicity, but many are not imported by the main crate.
 
+pub mod as_func;
 pub mod callbacks;
 pub mod class;
 pub mod constant;
 pub mod method;
 pub mod plugin;
 pub mod property;
+pub mod typed_signal;
 
 // RpcConfig uses MultiplayerPeer::TransferMode and MultiplayerApi::RpcMode, which are only enabled in `codegen-full` feature.
 #[cfg(feature = "codegen-full")]

godot-core/src/builtin/typed_signal.rs renamed to godot-core/src/registry/typed_signal.rs

@@ -7,56 +7,163 @@
 
 // Maybe move this to builtin::functional module?
 
-use crate::builtin::{Callable, Signal, Variant};
-use crate::obj::Gd;
+use crate::builtin::{Callable, Variant};
+use crate::obj::{Gd, GodotClass, WithBaseField};
+use crate::registry::as_func::AsFunc;
 use crate::{classes, meta, sys};
 use std::borrow::Cow;
 use std::fmt;
 
 pub trait ParamTuple {
     fn to_variant_array(&self) -> Vec<Variant>;
+    fn from_variant_array(array: &[&Variant]) -> Self;
 }
 
-impl ParamTuple for () {
-    fn to_variant_array(&self) -> Vec<Variant> {
-        Vec::new()
-    }
+macro_rules! impl_param_tuple {
+    // Recursive case for tuple with N elements
+    ($($args:ident : $Ps:ident),*) => {
+        impl<$($Ps),*> ParamTuple for ($($Ps,)*)
+        where
+            $($Ps: meta::ToGodot + meta::FromGodot),*
+        {
+            fn to_variant_array(&self) -> Vec<Variant> {
+                let ($($args,)*) = self;
+
+                vec![
+                    $( $args.to_variant(), )*
+                ]
+            }
+
+            #[allow(unused_variables, unused_mut)]
+            fn from_variant_array(array: &[&Variant]) -> Self {
+               let mut iter = array.iter();
+               ( $(
+                  <$Ps>::from_variant(
+                        iter.next().unwrap_or_else(|| panic!("ParamTuple: {} access out-of-bounds (len {})", stringify!($args), array.len()))
+                  ),
+               )* )
+            }
+        }
+    };
 }
 
-impl<T> ParamTuple for (T,)
+impl_param_tuple!();
+impl_param_tuple!(arg0: P0);
+impl_param_tuple!(arg0: P0, arg1: P1);
+impl_param_tuple!(arg0: P0, arg1: P1, arg2: P2);
+
+// ----------------------------------------------------------------------------------------------------------------------------------------------
+
+#[doc(hidden)]
+pub enum ObjectRef<'a, C: GodotClass> {
+    /// Helpful for emit: reuse `&self` from within the `impl` block, goes through `base()` re-borrowing and thus allows re-entrant calls
+    /// through Godot.
+    Internal { obj_mut: &'a mut C },
+
+    /// From outside, based on `Gd` pointer.
+    External { gd: Gd<C> },
+}
+
+impl<C> ObjectRef<'_, C>
 where
-    T: meta::ToGodot,
+    C: WithBaseField,
 {
-    fn to_variant_array(&self) -> Vec<Variant> {
-        vec![self.0.to_variant()]
+    fn with_object_mut(&mut self, f: impl FnOnce(&mut classes::Object)) {
+        match self {
+            ObjectRef::Internal { obj_mut } => f(obj_mut.base_mut().upcast_object_mut()),
+            ObjectRef::External { gd } => f(gd.upcast_object_mut()),
+        }
+    }
+
+    fn to_owned(&self) -> Gd<C> {
+        match self {
+            ObjectRef::Internal { obj_mut } => WithBaseField::to_gd(*obj_mut),
+            ObjectRef::External { gd } => gd.clone(),
+        }
     }
 }
 
 // ----------------------------------------------------------------------------------------------------------------------------------------------
 
-pub struct TypedSignal<Ps> {
-    signal: Signal,
+pub struct TypedSignal<'a, C: GodotClass, Ps> {
+    //signal: Signal,
+    /// In Godot, valid signals (unlike funcs) are _always_ declared in a class and become part of each instance. So there's always an object.
+    owner: ObjectRef<'a, C>,
+    name: Cow<'static, str>,
     _signature: std::marker::PhantomData<Ps>,
 }
 
-impl<Ps: ParamTuple> TypedSignal<Ps> {
-    pub(crate) fn from_untyped(signal: Signal) -> Self {
+impl<'a, C: WithBaseField, Ps: ParamTuple> TypedSignal<'a, C, Ps> {
+    #[doc(hidden)]
+    pub fn new(owner: ObjectRef<'a, C>, name: &'static str) -> Self {
         Self {
-            signal,
+            owner,
+            name: Cow::Borrowed(name),
             _signature: std::marker::PhantomData,
         }
     }
 
-    pub fn emit(&self, params: Ps) {
-        self.signal.emit(&params.to_variant_array());
+    pub fn emit(&mut self, params: Ps) {
+        let name = self.name.as_ref();
+
+        self.owner.with_object_mut(|obj| {
+            obj.emit_signal(name, &params.to_variant_array());
+        });
     }
 
-    pub fn connect_untyped(&mut self, callable: &Callable, flags: i64) {
-        self.signal.connect(callable, flags);
+    /// Connect a method (member function) with `&mut self` as the first parameter.
+    pub fn connect_self<F>(&mut self, mut function: F)
+    where
+        for<'c> F: AsFunc<&'c mut C, Ps> + 'static,
+    {
+        // When using sys::short_type_name() in the future, make sure global "func" and member "MyClass::func" are rendered as such.
+        // PascalCase heuristic should then be good enough.
+        let callable_name = std::any::type_name_of_val(&function);
+
+        let object = self.owner.to_owned();
+        let godot_fn = move |variant_args: &[&Variant]| -> Result<Variant, ()> {
+            let args = Ps::from_variant_array(variant_args);
+
+            // let mut function = function;
+            // function.call(instance, args);
+            let mut object = object.clone();
+
+            // TODO: how to avoid another bind, when emitting directly from Rust?
+            let mut instance = object.bind_mut();
+            let instance = &mut *instance;
+            function.call(instance, args);
+
+            Ok(Variant::nil())
+        };
+
+        let name = self.name.as_ref();
+        let callable = Callable::from_local_fn(callable_name, godot_fn);
+
+        self.owner.with_object_mut(|obj| {
+            obj.connect(name, &callable);
+        });
     }
 
-    pub fn to_untyped(&self) -> Signal {
-        self.signal.clone()
+    /// Connect a static function (global or associated function).
+    pub fn connect<F>(&mut self, mut function: F)
+    where
+        F: AsFunc<(), Ps> + 'static,
+    {
+        let callable_name = std::any::type_name_of_val(&function);
+
+        let godot_fn = move |variant_args: &[&Variant]| -> Result<Variant, ()> {
+            let args = Ps::from_variant_array(variant_args);
+            function.call((), args);
+
+            Ok(Variant::nil())
+        };
+
+        let name = self.name.as_ref();
+        let callable = Callable::from_local_fn(callable_name, godot_fn);
+
+        self.owner.with_object_mut(|obj| {
+            obj.connect(name, &callable);
+        });
     }
 }
 

godot-macros/src/class/data_models/func.rs

@@ -193,16 +193,16 @@ pub fn make_func_collection(
             static_collection_methods.push(quote! {
                 #(#cfg_attrs)*
                 // Use `&self` here to enable `.` chaining, such as in MyClass::static_funcs().my_func().
-                fn #rust_func_name(self) -> ::godot::builtin::Func<#generic_args> {
+                fn #rust_func_name(self) -> ::godot::register::Func<#generic_args> {
                     let class_name = <#class_name as ::godot::obj::GodotClass>::class_name();
-                    ::godot::builtin::Func::from_static_function(class_name.to_cow_str(), #godot_func_name)
+                    ::godot::register::Func::from_static_function(class_name.to_cow_str(), #godot_func_name)
                 }
             });
         } else {
             instance_collection_methods.push(quote! {
                 #(#cfg_attrs)*
-                fn #rust_func_name(self) -> ::godot::builtin::Func<#generic_args> {
-                    ::godot::builtin::Func::from_instance_method(self.obj, #godot_func_name)
+                fn #rust_func_name(self) -> ::godot::register::Func<#generic_args> {
+                    ::godot::register::Func::from_instance_method(self.obj, #godot_func_name)
                 }
             });
         }