Simplify system piping and make it more flexible

crates/bevy_ecs/src/system/system_piping.rs

@@ -73,29 +73,24 @@ where
 /// This trait is blanket implemented for all system pairs that fulfill the type requirements.
 ///
 /// See [`PipeSystem`].
-pub trait IntoPipeSystem<ParamA, Payload, SystemB, ParamB, Out>:
-    IntoSystem<(), Payload, ParamA> + Sized
-where
-    SystemB: IntoSystem<Payload, Out, ParamB>,
-{
+pub trait IntoPipeSystem<In, Payload, Marker>: IntoSystem<In, Payload, Marker> + Sized {
     /// Pass the output of this system `A` into a second system `B`, creating a new compound system.
-    fn pipe(self, system: SystemB) -> PipeSystem<Self::System, SystemB::System>;
-}
-
-impl<SystemA, ParamA, Payload, SystemB, ParamB, Out>
-    IntoPipeSystem<ParamA, Payload, SystemB, ParamB, Out> for SystemA
-where
-    SystemA: IntoSystem<(), Payload, ParamA>,
-    SystemB: IntoSystem<Payload, Out, ParamB>,
-{
-    fn pipe(self, system: SystemB) -> PipeSystem<SystemA::System, SystemB::System> {
+    fn pipe<B, Out, MarkerB>(self, system: B) -> PipeSystem<Self::System, B::System>
+    where
+        B: IntoSystem<Payload, Out, MarkerB>,
+    {
         let system_a = IntoSystem::into_system(self);
         let system_b = IntoSystem::into_system(system);
         let name = format!("Pipe({}, {})", system_a.name(), system_b.name());
         PipeSystem::new(system_a, system_b, Cow::Owned(name))
     }
 }
 
+impl<In, Payload, Marker, Sys> IntoPipeSystem<In, Payload, Marker> for Sys where
+    Sys: IntoSystem<In, Payload, Marker>
+{
+}
+
 /// A collection of common adapters for [piping](super::PipeSystem) the result of a system.
 pub mod adapter {
     use crate::system::In;
@@ -313,7 +308,7 @@ mod tests {
     use bevy_utils::default;
 
     use super::adapter::*;
-    use crate::{self as bevy_ecs, prelude::*, system::PipeSystem};
+    use crate::{self as bevy_ecs, prelude::*};
 
     #[test]
     fn assert_systems() {
@@ -384,11 +379,7 @@ mod tests {
 
         let mut world = World::new();
         world.init_resource::<Flag>();
-        let mut sys = PipeSystem::new(
-            IntoSystem::into_system(first),
-            IntoSystem::into_system(second),
-            "".into(),
-        );
+        let mut sys = first.pipe(second);
         sys.initialize(&mut world);
 
         sys.run(default(), &mut world);