Added PrettyPrintFunctionInfo

Used to help reduce code duplication for overloaded functions
and to give users the option to pretty-print FunctionInfo

crates/bevy_reflect/src/func/dynamic_function.rs

@@ -487,30 +487,17 @@ impl_type_path!((in bevy_reflect) DynamicFunction<'env>);
 /// This takes the format: `DynamicFunction(fn {name}({arg1}: {type1}, {arg2}: {type2}, ...) -> {return_type})`.
 ///
 /// Names for arguments and the function itself are optional and will default to `_` if not provided.
+///
+/// If the function is [overloaded], the output will include the signatures of all overloads as a set.
+/// For example, `DynamicFunction(fn add{(_: i32, _: i32) -> i32, (_: f32, _: f32) -> f32})`.
+///
+/// [overloaded]: DynamicFunction::with_overload
 impl<'env> Debug for DynamicFunction<'env> {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         let name = self.name().unwrap_or(&Cow::Borrowed("_"));
-        write!(f, "DynamicFunction(fn {name}(")?;
+        write!(f, "DynamicFunction(fn {name}")?;
-
+        self.function_map.debug(f)?;
-        match self.info() {
+        write!(f, ")")
-            FunctionInfoType::Standard(info) => {
-                for (index, arg) in info.args().iter().enumerate() {
-                    if index > 0 {
-                        write!(f, ", ")?;
-                    }
-
-                    let name = arg.name().unwrap_or("_");
-                    let ty = arg.type_path();
-                    write!(f, "{name}: {ty}")?;
-                }
-
-                let ret = info.return_info().type_path();
-                write!(f, ") -> {ret})")
-            }
-            FunctionInfoType::Overloaded(_) => {
-                todo!("overloaded functions are not yet debuggable");
-            }
-        }
     }
 }
 
@@ -825,4 +812,39 @@ mod tests {
             }
         );
     }
+
+    #[test]
+    fn should_debug_dynamic_function() {
+        fn greet(name: &String) -> String {
+            format!("Hello, {}!", name)
+        }
+
+        let function = greet.into_function();
+        let debug = format!("{:?}", function);
+        assert_eq!(debug, "DynamicFunction(fn bevy_reflect::func::dynamic_function::tests::should_debug_dynamic_function::greet(_: &alloc::string::String) -> alloc::string::String)");
+    }
+
+    #[test]
+    fn should_debug_anonymous_dynamic_function() {
+        let function = (|a: i32, b: i32| a + b).into_function();
+        let debug = format!("{:?}", function);
+        assert_eq!(debug, "DynamicFunction(fn _(_: i32, _: i32) -> i32)");
+    }
+
+    #[test]
+    fn should_debug_overloaded_dynamic_function() {
+        fn add<T: Add<Output = T>>(a: T, b: T) -> T {
+            a + b
+        }
+
+        let func = add::<i32>
+            .into_function()
+            .with_overload(add::<f32>)
+            .with_name("add");
+        let debug = format!("{:?}", func);
+        assert_eq!(
+            debug,
+            "DynamicFunction(fn add{(_: i32, _: i32) -> i32, (_: f32, _: f32) -> f32})"
+        );
+    }
 }

crates/bevy_reflect/src/func/dynamic_function_mut.rs

@@ -382,30 +382,17 @@ impl<'env> DynamicFunctionMut<'env> {
 /// This takes the format: `DynamicFunctionMut(fn {name}({arg1}: {type1}, {arg2}: {type2}, ...) -> {return_type})`.
 ///
 /// Names for arguments and the function itself are optional and will default to `_` if not provided.
+///
+/// If the function is [overloaded], the output will include the signatures of all overloads as a set.
+/// For example, `DynamicFunctionMut(fn add{(_: i32, _: i32) -> i32, (_: f32, _: f32) -> f32})`.
+///
+/// [overloaded]: DynamicFunctionMut::with_overload
 impl<'env> Debug for DynamicFunctionMut<'env> {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         let name = self.name().unwrap_or(&Cow::Borrowed("_"));
-        write!(f, "DynamicFunctionMut(fn {name}(")?;
+        write!(f, "DynamicFunctionMut(fn {name}")?;
-
+        self.function_map.debug(f)?;
-        match self.info() {
+        write!(f, ")")
-            FunctionInfoType::Standard(info) => {
-                for (index, arg) in info.args().iter().enumerate() {
-                    if index > 0 {
-                        write!(f, ", ")?;
-                    }
-
-                    let name = arg.name().unwrap_or("_");
-                    let ty = arg.type_path();
-                    write!(f, "{name}: {ty}")?;
-                }
-
-                let ret = info.return_info().type_path();
-                write!(f, ") -> {ret})")
-            }
-            FunctionInfoType::Overloaded(_) => {
-                todo!("overloaded functions are not yet debuggable");
-            }
-        }
     }
 }
 

crates/bevy_reflect/src/func/function_map.rs

@@ -1,7 +1,11 @@
 use crate::func::signature::ArgumentSignature;
-use crate::func::{ArgList, FunctionError, FunctionInfo, FunctionInfoType, FunctionOverloadError};
+use crate::func::{
+    ArgList, FunctionError, FunctionInfo, FunctionInfoType, FunctionOverloadError,
+    PrettyPrintFunctionInfo,
+};
 use alloc::borrow::Cow;
 use bevy_utils::hashbrown::HashMap;
+use core::fmt::{Debug, Formatter};
 use core::ops::RangeInclusive;
 
 /// A helper type for storing a mapping of overloaded functions
@@ -216,6 +220,21 @@ impl<F> FunctionMap<F> {
             }
         }
     }
+
+    pub fn debug(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            // `(arg0: i32, arg1: i32) -> ()`
+            Self::Single(_, info) => PrettyPrintFunctionInfo::new(info).fmt(f),
+            // `{(arg0: i32, arg1: i32) -> (), (arg0: f32, arg1: f32) -> ()}`
+            Self::Overloaded(_, infos, _) => {
+                let mut set = f.debug_set();
+                for info in infos.iter() {
+                    set.entry(&PrettyPrintFunctionInfo::new(info));
+                }
+                set.finish()
+            }
+        }
+    }
 }
 
 #[cfg(test)]

crates/bevy_reflect/src/func/info.rs

@@ -3,6 +3,7 @@ use alloc::{borrow::Cow, vec};
 #[cfg(not(feature = "std"))]
 use alloc::{boxed::Box, format, vec};
 
+use core::fmt::{Debug, Formatter};
 use core::ops::RangeInclusive;
 use variadics_please::all_tuples;
 
@@ -211,6 +212,28 @@ impl FunctionInfo {
     pub fn return_info(&self) -> &ReturnInfo {
         &self.return_info
     }
+
+    /// Returns a wrapper around this info that implements [`Debug`] for pretty-printing the function.
+    ///
+    /// This can be useful for more readable debugging and logging.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use bevy_reflect::func::{FunctionInfo, TypedFunction};
+    /// #
+    /// fn add(a: i32, b: i32) -> i32 {
+    ///     a + b
+    /// }
+    ///
+    /// let info = add.get_function_info();
+    ///
+    /// let pretty = info.pretty_printer();
+    /// assert_eq!(format!("{:?}", pretty), "(_: i32, _: i32) -> i32");
+    /// ```
+    pub fn pretty_printer(&self) -> PrettyPrintFunctionInfo {
+        PrettyPrintFunctionInfo::new(self)
+    }
 }
 
 /// Information about the return type of a [`DynamicFunction`] or [`DynamicFunctionMut`].
@@ -240,6 +263,86 @@ impl ReturnInfo {
     }
 }
 
+/// A wrapper around [`FunctionInfo`] that implements [`Debug`] for pretty-printing function information.
+///
+/// # Example
+///
+/// ```
+/// # use bevy_reflect::func::{FunctionInfo, PrettyPrintFunctionInfo, TypedFunction};
+/// #
+/// fn add(a: i32, b: i32) -> i32 {
+///     a + b
+/// }
+///
+/// let info = add.get_function_info();
+///
+/// let pretty = PrettyPrintFunctionInfo::new(&info);
+/// assert_eq!(format!("{:?}", pretty), "(_: i32, _: i32) -> i32");
+/// ```
+pub struct PrettyPrintFunctionInfo<'a> {
+    info: &'a FunctionInfo,
+    include_fn_token: bool,
+    include_name: bool,
+}
+
+impl<'a> PrettyPrintFunctionInfo<'a> {
+    /// Create a new pretty-printer for the given [`FunctionInfo`].
+    pub fn new(info: &'a FunctionInfo) -> Self {
+        Self {
+            info,
+            include_fn_token: false,
+            include_name: false,
+        }
+    }
+
+    /// Include the function name in the pretty-printed output.
+    pub fn include_name(mut self) -> Self {
+        self.include_name = true;
+        self
+    }
+
+    /// Include the `fn` token in the pretty-printed output.
+    pub fn include_fn_token(mut self) -> Self {
+        self.include_fn_token = true;
+        self
+    }
+}
+
+impl<'a> Debug for PrettyPrintFunctionInfo<'a> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        if self.include_fn_token {
+            write!(f, "fn")?;
+
+            if self.include_name {
+                write!(f, " ")?;
+            }
+        }
+
+        match (self.include_name, self.info.name()) {
+            (true, Some(name)) => write!(f, "{}", name)?,
+            (true, None) => write!(f, "_")?,
+            _ => {}
+        }
+
+        write!(f, "(")?;
+
+        // We manually write the args instead of using `DebugTuple` to avoid trailing commas
+        // and (when used with `{:#?}`) unnecessary newlines
+        for (index, arg) in self.info.args().iter().enumerate() {
+            if index > 0 {
+                write!(f, ", ")?;
+            }
+
+            let name = arg.name().unwrap_or("_");
+            let ty = arg.type_path();
+            write!(f, "{name}: {ty}")?;
+        }
+
+        let ret = self.info.return_info().type_path();
+        write!(f, ") -> {ret}")
+    }
+}
+
 /// A static accessor to compile-time type information for functions.
 ///
 /// This is the equivalent of [`Typed`], but for function.
@@ -520,4 +623,25 @@ mod tests {
         assert_eq!(info.args()[1].type_path(), "i32");
         assert_eq!(info.return_info().type_path(), "()");
     }
+
+    #[test]
+    fn should_pretty_print_info() {
+        fn add(a: i32, b: i32) -> i32 {
+            a + b
+        }
+
+        let info = add.get_function_info().with_name("add");
+
+        let pretty = info.pretty_printer();
+        assert_eq!(format!("{:?}", pretty), "(_: i32, _: i32) -> i32");
+
+        let pretty = info.pretty_printer().include_fn_token();
+        assert_eq!(format!("{:?}", pretty), "fn(_: i32, _: i32) -> i32");
+
+        let pretty = info.pretty_printer().include_name();
+        assert_eq!(format!("{:?}", pretty), "add(_: i32, _: i32) -> i32");
+
+        let pretty = info.pretty_printer().include_fn_token().include_name();
+        assert_eq!(format!("{:?}", pretty), "fn add(_: i32, _: i32) -> i32");
+    }
 }