Struct SignatureInfo 

pub struct SignatureInfo { /* private fields */ }

Available on crate feature functions only.

Type information for the signature of a DynamicFunction or DynamicFunctionMut.

Every FunctionInfo contains one or more SignatureInfos.

Implementations

impl SignatureInfo

pub fn named(name: impl Into<Cow<'static, str>>) -> SignatureInfo

Create a new SignatureInfo for a function with the given name.

Examples found in repository

examples/reflection/function_reflection.rs (line 196)

fn main() {
    // There are times when it may be helpful to store a function away for later.
    // In Rust, we can do this by storing either a function pointer or a function trait object.
    // For example, say we wanted to store the following function:
    fn add(left: i32, right: i32) -> i32 {
        left + right
    }

    // We could store it as either of the following:
    let fn_pointer: fn(i32, i32) -> i32 = add;
    let fn_trait_object: Box<dyn Fn(i32, i32) -> i32> = Box::new(add);

    // And we can call them like so:
    let result = fn_pointer(2, 2);
    assert_eq!(result, 4);
    let result = fn_trait_object(2, 2);
    assert_eq!(result, 4);

    // However, you'll notice that we have to know the types of the arguments and return value at compile time.
    // This means there's not really a way to store or call these functions dynamically at runtime.
    // Luckily, Bevy's reflection crate comes with a set of tools for doing just that!
    // We do this by first converting our function into the reflection-based `DynamicFunction` type
    // using the `IntoFunction` trait.
    let function: DynamicFunction<'static> = dbg!(add.into_function());

    // This time, you'll notice that `DynamicFunction` doesn't take any information about the function's arguments or return value.
    // This is because `DynamicFunction` checks the types of the arguments and return value at runtime.
    // Now we can generate a list of arguments:
    let args: ArgList = dbg!(ArgList::new().with_owned(2_i32).with_owned(2_i32));

    // And finally, we can call the function.
    // This returns a `Result` indicating whether the function was called successfully.
    // For now, we'll just unwrap it to get our `Return` value,
    // which is an enum containing the function's return value.
    let return_value: Return = dbg!(function.call(args).unwrap());

    // The `Return` value can be pattern matched or unwrapped to get the underlying reflection data.
    // For the sake of brevity, we'll just unwrap it here and downcast it to the expected type of `i32`.
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 4);

    // The same can also be done for closures that capture references to their environment.
    // Closures that capture their environment immutably can be converted into a `DynamicFunction`
    // using the `IntoFunction` trait.
    let minimum = 5;
    let clamp = |value: i32| value.max(minimum);

    let function: DynamicFunction = dbg!(clamp.into_function());
    let args = dbg!(ArgList::new().with_owned(2_i32));
    let return_value = dbg!(function.call(args).unwrap());
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 5);

    // We can also handle closures that capture their environment mutably
    // using the `IntoFunctionMut` trait.
    let mut count = 0;
    let increment = |amount: i32| count += amount;

    let closure: DynamicFunctionMut = dbg!(increment.into_function_mut());
    let args = dbg!(ArgList::new().with_owned(5_i32));

    // Because `DynamicFunctionMut` mutably borrows `total`,
    // it will need to be dropped before `total` can be accessed again.
    // This can be done manually with `drop(closure)` or by using the `DynamicFunctionMut::call_once` method.
    dbg!(closure.call_once(args).unwrap());
    assert_eq!(count, 5);

    // Generic functions can also be converted into a `DynamicFunction`,
    // however, they will need to be manually monomorphized first.
    fn stringify<T: ToString>(value: T) -> String {
        value.to_string()
    }

    // We have to manually specify the concrete generic type we want to use.
    let function = stringify::<i32>.into_function();

    let args = ArgList::new().with_owned(123_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "123");

    // To make things a little easier, we can also "overload" functions.
    // This makes it so that a single `DynamicFunction` can represent multiple functions,
    // and the correct one is chosen based on the types of the arguments.
    // Each function overload must have a unique argument signature.
    let function = stringify::<i32>
        .into_function()
        .with_overload(stringify::<f32>);

    // Now our `function` accepts both `i32` and `f32` arguments.
    let args = ArgList::new().with_owned(1.23_f32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "1.23");

    // Function overloading even allows us to have a variable number of arguments.
    let function = (|| 0)
        .into_function()
        .with_overload(|a: i32| a)
        .with_overload(|a: i32, b: i32| a + b)
        .with_overload(|a: i32, b: i32, c: i32| a + b + c);

    let args = ArgList::new()
        .with_owned(1_i32)
        .with_owned(2_i32)
        .with_owned(3_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 6);

    // As stated earlier, `IntoFunction` works for many kinds of simple functions.
    // Functions with non-reflectable arguments or return values may not be able to be converted.
    // Generic functions are also not supported (unless manually monomorphized like `foo::<i32>.into_function()`).
    // Additionally, the lifetime of the return value is tied to the lifetime of the first argument.
    // However, this means that many methods (i.e. functions with a `self` parameter) are also supported:
    #[derive(Reflect, Default)]
    struct Data {
        value: String,
    }

    impl Data {
        fn set_value(&mut self, value: String) {
            self.value = value;
        }

        // Note that only `&'static str` implements `Reflect`.
        // To get around this limitation we can use `&String` instead.
        fn get_value(&self) -> &String {
            &self.value
        }
    }

    let mut data = Data::default();

    let set_value = dbg!(Data::set_value.into_function());
    let args = dbg!(ArgList::new().with_mut(&mut data)).with_owned(String::from("Hello, world!"));
    dbg!(set_value.call(args).unwrap());
    assert_eq!(data.value, "Hello, world!");

    let get_value = dbg!(Data::get_value.into_function());
    let args = dbg!(ArgList::new().with_ref(&data));
    let return_value = dbg!(get_value.call(args).unwrap());
    let value: &dyn PartialReflect = return_value.unwrap_ref();
    assert_eq!(value.try_downcast_ref::<String>().unwrap(), "Hello, world!");

    // For more complex use cases, you can always create a custom `DynamicFunction` manually.
    // This is useful for functions that can't be converted via the `IntoFunction` trait.
    // For example, this function doesn't implement `IntoFunction` due to the fact that
    // the lifetime of the return value is not tied to the lifetime of the first argument.
    fn get_or_insert(value: i32, container: &mut Option<i32>) -> &i32 {
        if container.is_none() {
            *container = Some(value);
        }

        container.as_ref().unwrap()
    }

    let get_or_insert_function = dbg!(DynamicFunction::new(
        |mut args: ArgList| -> FunctionResult {
            // The `ArgList` contains the arguments in the order they were pushed.
            // The `DynamicFunction` will validate that the list contains
            // exactly the number of arguments we expect.
            // We can retrieve them out in order (note that this modifies the `ArgList`):
            let value = args.take::<i32>()?;
            let container = args.take::<&mut Option<i32>>()?;

            // We could have also done the following to make use of type inference:
            // let value = args.take_owned()?;
            // let container = args.take_mut()?;

            Ok(Return::Ref(get_or_insert(value, container)))
        },
        // Functions can be either anonymous or named.
        // It's good practice, though, to try and name your functions whenever possible.
        // This makes it easier to debug and is also required for function registration.
        // We can either give it a custom name or use the function's type name as
        // derived from `std::any::type_name_of_val`.
        SignatureInfo::named(std::any::type_name_of_val(&get_or_insert))
            // We can always change the name if needed.
            // It's a good idea to also ensure that the name is unique,
            // such as by using its type name or by prefixing it with your crate name.
            .with_name("my_crate::get_or_insert")
            // Since our function takes arguments, we should provide that argument information.
            // This is used to validate arguments when calling the function.
            // And it aids consumers of the function with their own validation and debugging.
            // Arguments should be provided in the order they are defined in the function.
            .with_arg::<i32>("value")
            .with_arg::<&mut Option<i32>>("container")
            // We can provide return information as well.
            .with_return::<&i32>(),
    ));

    let mut container: Option<i32> = None;

    let args = dbg!(ArgList::new().with_owned(5_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));

    let args = dbg!(ArgList::new().with_owned(500_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));
}

pub fn anonymous() -> SignatureInfo

Create a new SignatureInfo with no name.

For the purposes of debugging and registration, it’s recommended to use Self::named instead.

pub fn with_name(self, name: impl Into<Cow<'static, str>>) -> SignatureInfo

Set the name of the function.

Examples found in repository

examples/reflection/function_reflection.rs (line 200)

fn main() {
    // There are times when it may be helpful to store a function away for later.
    // In Rust, we can do this by storing either a function pointer or a function trait object.
    // For example, say we wanted to store the following function:
    fn add(left: i32, right: i32) -> i32 {
        left + right
    }

    // We could store it as either of the following:
    let fn_pointer: fn(i32, i32) -> i32 = add;
    let fn_trait_object: Box<dyn Fn(i32, i32) -> i32> = Box::new(add);

    // And we can call them like so:
    let result = fn_pointer(2, 2);
    assert_eq!(result, 4);
    let result = fn_trait_object(2, 2);
    assert_eq!(result, 4);

    // However, you'll notice that we have to know the types of the arguments and return value at compile time.
    // This means there's not really a way to store or call these functions dynamically at runtime.
    // Luckily, Bevy's reflection crate comes with a set of tools for doing just that!
    // We do this by first converting our function into the reflection-based `DynamicFunction` type
    // using the `IntoFunction` trait.
    let function: DynamicFunction<'static> = dbg!(add.into_function());

    // This time, you'll notice that `DynamicFunction` doesn't take any information about the function's arguments or return value.
    // This is because `DynamicFunction` checks the types of the arguments and return value at runtime.
    // Now we can generate a list of arguments:
    let args: ArgList = dbg!(ArgList::new().with_owned(2_i32).with_owned(2_i32));

    // And finally, we can call the function.
    // This returns a `Result` indicating whether the function was called successfully.
    // For now, we'll just unwrap it to get our `Return` value,
    // which is an enum containing the function's return value.
    let return_value: Return = dbg!(function.call(args).unwrap());

    // The `Return` value can be pattern matched or unwrapped to get the underlying reflection data.
    // For the sake of brevity, we'll just unwrap it here and downcast it to the expected type of `i32`.
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 4);

    // The same can also be done for closures that capture references to their environment.
    // Closures that capture their environment immutably can be converted into a `DynamicFunction`
    // using the `IntoFunction` trait.
    let minimum = 5;
    let clamp = |value: i32| value.max(minimum);

    let function: DynamicFunction = dbg!(clamp.into_function());
    let args = dbg!(ArgList::new().with_owned(2_i32));
    let return_value = dbg!(function.call(args).unwrap());
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 5);

    // We can also handle closures that capture their environment mutably
    // using the `IntoFunctionMut` trait.
    let mut count = 0;
    let increment = |amount: i32| count += amount;

    let closure: DynamicFunctionMut = dbg!(increment.into_function_mut());
    let args = dbg!(ArgList::new().with_owned(5_i32));

    // Because `DynamicFunctionMut` mutably borrows `total`,
    // it will need to be dropped before `total` can be accessed again.
    // This can be done manually with `drop(closure)` or by using the `DynamicFunctionMut::call_once` method.
    dbg!(closure.call_once(args).unwrap());
    assert_eq!(count, 5);

    // Generic functions can also be converted into a `DynamicFunction`,
    // however, they will need to be manually monomorphized first.
    fn stringify<T: ToString>(value: T) -> String {
        value.to_string()
    }

    // We have to manually specify the concrete generic type we want to use.
    let function = stringify::<i32>.into_function();

    let args = ArgList::new().with_owned(123_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "123");

    // To make things a little easier, we can also "overload" functions.
    // This makes it so that a single `DynamicFunction` can represent multiple functions,
    // and the correct one is chosen based on the types of the arguments.
    // Each function overload must have a unique argument signature.
    let function = stringify::<i32>
        .into_function()
        .with_overload(stringify::<f32>);

    // Now our `function` accepts both `i32` and `f32` arguments.
    let args = ArgList::new().with_owned(1.23_f32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "1.23");

    // Function overloading even allows us to have a variable number of arguments.
    let function = (|| 0)
        .into_function()
        .with_overload(|a: i32| a)
        .with_overload(|a: i32, b: i32| a + b)
        .with_overload(|a: i32, b: i32, c: i32| a + b + c);

    let args = ArgList::new()
        .with_owned(1_i32)
        .with_owned(2_i32)
        .with_owned(3_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 6);

    // As stated earlier, `IntoFunction` works for many kinds of simple functions.
    // Functions with non-reflectable arguments or return values may not be able to be converted.
    // Generic functions are also not supported (unless manually monomorphized like `foo::<i32>.into_function()`).
    // Additionally, the lifetime of the return value is tied to the lifetime of the first argument.
    // However, this means that many methods (i.e. functions with a `self` parameter) are also supported:
    #[derive(Reflect, Default)]
    struct Data {
        value: String,
    }

    impl Data {
        fn set_value(&mut self, value: String) {
            self.value = value;
        }

        // Note that only `&'static str` implements `Reflect`.
        // To get around this limitation we can use `&String` instead.
        fn get_value(&self) -> &String {
            &self.value
        }
    }

    let mut data = Data::default();

    let set_value = dbg!(Data::set_value.into_function());
    let args = dbg!(ArgList::new().with_mut(&mut data)).with_owned(String::from("Hello, world!"));
    dbg!(set_value.call(args).unwrap());
    assert_eq!(data.value, "Hello, world!");

    let get_value = dbg!(Data::get_value.into_function());
    let args = dbg!(ArgList::new().with_ref(&data));
    let return_value = dbg!(get_value.call(args).unwrap());
    let value: &dyn PartialReflect = return_value.unwrap_ref();
    assert_eq!(value.try_downcast_ref::<String>().unwrap(), "Hello, world!");

    // For more complex use cases, you can always create a custom `DynamicFunction` manually.
    // This is useful for functions that can't be converted via the `IntoFunction` trait.
    // For example, this function doesn't implement `IntoFunction` due to the fact that
    // the lifetime of the return value is not tied to the lifetime of the first argument.
    fn get_or_insert(value: i32, container: &mut Option<i32>) -> &i32 {
        if container.is_none() {
            *container = Some(value);
        }

        container.as_ref().unwrap()
    }

    let get_or_insert_function = dbg!(DynamicFunction::new(
        |mut args: ArgList| -> FunctionResult {
            // The `ArgList` contains the arguments in the order they were pushed.
            // The `DynamicFunction` will validate that the list contains
            // exactly the number of arguments we expect.
            // We can retrieve them out in order (note that this modifies the `ArgList`):
            let value = args.take::<i32>()?;
            let container = args.take::<&mut Option<i32>>()?;

            // We could have also done the following to make use of type inference:
            // let value = args.take_owned()?;
            // let container = args.take_mut()?;

            Ok(Return::Ref(get_or_insert(value, container)))
        },
        // Functions can be either anonymous or named.
        // It's good practice, though, to try and name your functions whenever possible.
        // This makes it easier to debug and is also required for function registration.
        // We can either give it a custom name or use the function's type name as
        // derived from `std::any::type_name_of_val`.
        SignatureInfo::named(std::any::type_name_of_val(&get_or_insert))
            // We can always change the name if needed.
            // It's a good idea to also ensure that the name is unique,
            // such as by using its type name or by prefixing it with your crate name.
            .with_name("my_crate::get_or_insert")
            // Since our function takes arguments, we should provide that argument information.
            // This is used to validate arguments when calling the function.
            // And it aids consumers of the function with their own validation and debugging.
            // Arguments should be provided in the order they are defined in the function.
            .with_arg::<i32>("value")
            .with_arg::<&mut Option<i32>>("container")
            // We can provide return information as well.
            .with_return::<&i32>(),
    ));

    let mut container: Option<i32> = None;

    let args = dbg!(ArgList::new().with_owned(5_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));

    let args = dbg!(ArgList::new().with_owned(500_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));
}

pub fn with_arg<T>(self, name: impl Into<Cow<'static, str>>) -> SignatureInfo

where T: TypePath + GetOwnership,

Push an argument onto the function’s argument list.

The order in which this method is called matters as it will determine the index of the argument based on the current number of arguments.

Examples found in repository

examples/reflection/function_reflection.rs (line 205)

fn main() {
    // There are times when it may be helpful to store a function away for later.
    // In Rust, we can do this by storing either a function pointer or a function trait object.
    // For example, say we wanted to store the following function:
    fn add(left: i32, right: i32) -> i32 {
        left + right
    }

    // We could store it as either of the following:
    let fn_pointer: fn(i32, i32) -> i32 = add;
    let fn_trait_object: Box<dyn Fn(i32, i32) -> i32> = Box::new(add);

    // And we can call them like so:
    let result = fn_pointer(2, 2);
    assert_eq!(result, 4);
    let result = fn_trait_object(2, 2);
    assert_eq!(result, 4);

    // However, you'll notice that we have to know the types of the arguments and return value at compile time.
    // This means there's not really a way to store or call these functions dynamically at runtime.
    // Luckily, Bevy's reflection crate comes with a set of tools for doing just that!
    // We do this by first converting our function into the reflection-based `DynamicFunction` type
    // using the `IntoFunction` trait.
    let function: DynamicFunction<'static> = dbg!(add.into_function());

    // This time, you'll notice that `DynamicFunction` doesn't take any information about the function's arguments or return value.
    // This is because `DynamicFunction` checks the types of the arguments and return value at runtime.
    // Now we can generate a list of arguments:
    let args: ArgList = dbg!(ArgList::new().with_owned(2_i32).with_owned(2_i32));

    // And finally, we can call the function.
    // This returns a `Result` indicating whether the function was called successfully.
    // For now, we'll just unwrap it to get our `Return` value,
    // which is an enum containing the function's return value.
    let return_value: Return = dbg!(function.call(args).unwrap());

    // The `Return` value can be pattern matched or unwrapped to get the underlying reflection data.
    // For the sake of brevity, we'll just unwrap it here and downcast it to the expected type of `i32`.
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 4);

    // The same can also be done for closures that capture references to their environment.
    // Closures that capture their environment immutably can be converted into a `DynamicFunction`
    // using the `IntoFunction` trait.
    let minimum = 5;
    let clamp = |value: i32| value.max(minimum);

    let function: DynamicFunction = dbg!(clamp.into_function());
    let args = dbg!(ArgList::new().with_owned(2_i32));
    let return_value = dbg!(function.call(args).unwrap());
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 5);

    // We can also handle closures that capture their environment mutably
    // using the `IntoFunctionMut` trait.
    let mut count = 0;
    let increment = |amount: i32| count += amount;

    let closure: DynamicFunctionMut = dbg!(increment.into_function_mut());
    let args = dbg!(ArgList::new().with_owned(5_i32));

    // Because `DynamicFunctionMut` mutably borrows `total`,
    // it will need to be dropped before `total` can be accessed again.
    // This can be done manually with `drop(closure)` or by using the `DynamicFunctionMut::call_once` method.
    dbg!(closure.call_once(args).unwrap());
    assert_eq!(count, 5);

    // Generic functions can also be converted into a `DynamicFunction`,
    // however, they will need to be manually monomorphized first.
    fn stringify<T: ToString>(value: T) -> String {
        value.to_string()
    }

    // We have to manually specify the concrete generic type we want to use.
    let function = stringify::<i32>.into_function();

    let args = ArgList::new().with_owned(123_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "123");

    // To make things a little easier, we can also "overload" functions.
    // This makes it so that a single `DynamicFunction` can represent multiple functions,
    // and the correct one is chosen based on the types of the arguments.
    // Each function overload must have a unique argument signature.
    let function = stringify::<i32>
        .into_function()
        .with_overload(stringify::<f32>);

    // Now our `function` accepts both `i32` and `f32` arguments.
    let args = ArgList::new().with_owned(1.23_f32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "1.23");

    // Function overloading even allows us to have a variable number of arguments.
    let function = (|| 0)
        .into_function()
        .with_overload(|a: i32| a)
        .with_overload(|a: i32, b: i32| a + b)
        .with_overload(|a: i32, b: i32, c: i32| a + b + c);

    let args = ArgList::new()
        .with_owned(1_i32)
        .with_owned(2_i32)
        .with_owned(3_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 6);

    // As stated earlier, `IntoFunction` works for many kinds of simple functions.
    // Functions with non-reflectable arguments or return values may not be able to be converted.
    // Generic functions are also not supported (unless manually monomorphized like `foo::<i32>.into_function()`).
    // Additionally, the lifetime of the return value is tied to the lifetime of the first argument.
    // However, this means that many methods (i.e. functions with a `self` parameter) are also supported:
    #[derive(Reflect, Default)]
    struct Data {
        value: String,
    }

    impl Data {
        fn set_value(&mut self, value: String) {
            self.value = value;
        }

        // Note that only `&'static str` implements `Reflect`.
        // To get around this limitation we can use `&String` instead.
        fn get_value(&self) -> &String {
            &self.value
        }
    }

    let mut data = Data::default();

    let set_value = dbg!(Data::set_value.into_function());
    let args = dbg!(ArgList::new().with_mut(&mut data)).with_owned(String::from("Hello, world!"));
    dbg!(set_value.call(args).unwrap());
    assert_eq!(data.value, "Hello, world!");

    let get_value = dbg!(Data::get_value.into_function());
    let args = dbg!(ArgList::new().with_ref(&data));
    let return_value = dbg!(get_value.call(args).unwrap());
    let value: &dyn PartialReflect = return_value.unwrap_ref();
    assert_eq!(value.try_downcast_ref::<String>().unwrap(), "Hello, world!");

    // For more complex use cases, you can always create a custom `DynamicFunction` manually.
    // This is useful for functions that can't be converted via the `IntoFunction` trait.
    // For example, this function doesn't implement `IntoFunction` due to the fact that
    // the lifetime of the return value is not tied to the lifetime of the first argument.
    fn get_or_insert(value: i32, container: &mut Option<i32>) -> &i32 {
        if container.is_none() {
            *container = Some(value);
        }

        container.as_ref().unwrap()
    }

    let get_or_insert_function = dbg!(DynamicFunction::new(
        |mut args: ArgList| -> FunctionResult {
            // The `ArgList` contains the arguments in the order they were pushed.
            // The `DynamicFunction` will validate that the list contains
            // exactly the number of arguments we expect.
            // We can retrieve them out in order (note that this modifies the `ArgList`):
            let value = args.take::<i32>()?;
            let container = args.take::<&mut Option<i32>>()?;

            // We could have also done the following to make use of type inference:
            // let value = args.take_owned()?;
            // let container = args.take_mut()?;

            Ok(Return::Ref(get_or_insert(value, container)))
        },
        // Functions can be either anonymous or named.
        // It's good practice, though, to try and name your functions whenever possible.
        // This makes it easier to debug and is also required for function registration.
        // We can either give it a custom name or use the function's type name as
        // derived from `std::any::type_name_of_val`.
        SignatureInfo::named(std::any::type_name_of_val(&get_or_insert))
            // We can always change the name if needed.
            // It's a good idea to also ensure that the name is unique,
            // such as by using its type name or by prefixing it with your crate name.
            .with_name("my_crate::get_or_insert")
            // Since our function takes arguments, we should provide that argument information.
            // This is used to validate arguments when calling the function.
            // And it aids consumers of the function with their own validation and debugging.
            // Arguments should be provided in the order they are defined in the function.
            .with_arg::<i32>("value")
            .with_arg::<&mut Option<i32>>("container")
            // We can provide return information as well.
            .with_return::<&i32>(),
    ));

    let mut container: Option<i32> = None;

    let args = dbg!(ArgList::new().with_owned(5_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));

    let args = dbg!(ArgList::new().with_owned(500_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));
}

pub fn with_args(self, args: Vec<ArgInfo>) -> SignatureInfo

Set the arguments of the function.

This will completely replace any existing arguments.

It’s preferable to use Self::with_arg to add arguments to the function as it will automatically set the index of the argument.

pub fn with_return<T>(self) -> SignatureInfo

where T: TypePath + GetOwnership,

Set the return information of the function.

To manually set the ReturnInfo of the function, see Self::with_return_info.

Examples found in repository

examples/reflection/function_reflection.rs (line 208)

fn main() {
    // There are times when it may be helpful to store a function away for later.
    // In Rust, we can do this by storing either a function pointer or a function trait object.
    // For example, say we wanted to store the following function:
    fn add(left: i32, right: i32) -> i32 {
        left + right
    }

    // We could store it as either of the following:
    let fn_pointer: fn(i32, i32) -> i32 = add;
    let fn_trait_object: Box<dyn Fn(i32, i32) -> i32> = Box::new(add);

    // And we can call them like so:
    let result = fn_pointer(2, 2);
    assert_eq!(result, 4);
    let result = fn_trait_object(2, 2);
    assert_eq!(result, 4);

    // However, you'll notice that we have to know the types of the arguments and return value at compile time.
    // This means there's not really a way to store or call these functions dynamically at runtime.
    // Luckily, Bevy's reflection crate comes with a set of tools for doing just that!
    // We do this by first converting our function into the reflection-based `DynamicFunction` type
    // using the `IntoFunction` trait.
    let function: DynamicFunction<'static> = dbg!(add.into_function());

    // This time, you'll notice that `DynamicFunction` doesn't take any information about the function's arguments or return value.
    // This is because `DynamicFunction` checks the types of the arguments and return value at runtime.
    // Now we can generate a list of arguments:
    let args: ArgList = dbg!(ArgList::new().with_owned(2_i32).with_owned(2_i32));

    // And finally, we can call the function.
    // This returns a `Result` indicating whether the function was called successfully.
    // For now, we'll just unwrap it to get our `Return` value,
    // which is an enum containing the function's return value.
    let return_value: Return = dbg!(function.call(args).unwrap());

    // The `Return` value can be pattern matched or unwrapped to get the underlying reflection data.
    // For the sake of brevity, we'll just unwrap it here and downcast it to the expected type of `i32`.
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 4);

    // The same can also be done for closures that capture references to their environment.
    // Closures that capture their environment immutably can be converted into a `DynamicFunction`
    // using the `IntoFunction` trait.
    let minimum = 5;
    let clamp = |value: i32| value.max(minimum);

    let function: DynamicFunction = dbg!(clamp.into_function());
    let args = dbg!(ArgList::new().with_owned(2_i32));
    let return_value = dbg!(function.call(args).unwrap());
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 5);

    // We can also handle closures that capture their environment mutably
    // using the `IntoFunctionMut` trait.
    let mut count = 0;
    let increment = |amount: i32| count += amount;

    let closure: DynamicFunctionMut = dbg!(increment.into_function_mut());
    let args = dbg!(ArgList::new().with_owned(5_i32));

    // Because `DynamicFunctionMut` mutably borrows `total`,
    // it will need to be dropped before `total` can be accessed again.
    // This can be done manually with `drop(closure)` or by using the `DynamicFunctionMut::call_once` method.
    dbg!(closure.call_once(args).unwrap());
    assert_eq!(count, 5);

    // Generic functions can also be converted into a `DynamicFunction`,
    // however, they will need to be manually monomorphized first.
    fn stringify<T: ToString>(value: T) -> String {
        value.to_string()
    }

    // We have to manually specify the concrete generic type we want to use.
    let function = stringify::<i32>.into_function();

    let args = ArgList::new().with_owned(123_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "123");

    // To make things a little easier, we can also "overload" functions.
    // This makes it so that a single `DynamicFunction` can represent multiple functions,
    // and the correct one is chosen based on the types of the arguments.
    // Each function overload must have a unique argument signature.
    let function = stringify::<i32>
        .into_function()
        .with_overload(stringify::<f32>);

    // Now our `function` accepts both `i32` and `f32` arguments.
    let args = ArgList::new().with_owned(1.23_f32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<String>().unwrap(), "1.23");

    // Function overloading even allows us to have a variable number of arguments.
    let function = (|| 0)
        .into_function()
        .with_overload(|a: i32| a)
        .with_overload(|a: i32, b: i32| a + b)
        .with_overload(|a: i32, b: i32, c: i32| a + b + c);

    let args = ArgList::new()
        .with_owned(1_i32)
        .with_owned(2_i32)
        .with_owned(3_i32);
    let return_value = function.call(args).unwrap();
    let value: Box<dyn PartialReflect> = return_value.unwrap_owned();
    assert_eq!(value.try_take::<i32>().unwrap(), 6);

    // As stated earlier, `IntoFunction` works for many kinds of simple functions.
    // Functions with non-reflectable arguments or return values may not be able to be converted.
    // Generic functions are also not supported (unless manually monomorphized like `foo::<i32>.into_function()`).
    // Additionally, the lifetime of the return value is tied to the lifetime of the first argument.
    // However, this means that many methods (i.e. functions with a `self` parameter) are also supported:
    #[derive(Reflect, Default)]
    struct Data {
        value: String,
    }

    impl Data {
        fn set_value(&mut self, value: String) {
            self.value = value;
        }

        // Note that only `&'static str` implements `Reflect`.
        // To get around this limitation we can use `&String` instead.
        fn get_value(&self) -> &String {
            &self.value
        }
    }

    let mut data = Data::default();

    let set_value = dbg!(Data::set_value.into_function());
    let args = dbg!(ArgList::new().with_mut(&mut data)).with_owned(String::from("Hello, world!"));
    dbg!(set_value.call(args).unwrap());
    assert_eq!(data.value, "Hello, world!");

    let get_value = dbg!(Data::get_value.into_function());
    let args = dbg!(ArgList::new().with_ref(&data));
    let return_value = dbg!(get_value.call(args).unwrap());
    let value: &dyn PartialReflect = return_value.unwrap_ref();
    assert_eq!(value.try_downcast_ref::<String>().unwrap(), "Hello, world!");

    // For more complex use cases, you can always create a custom `DynamicFunction` manually.
    // This is useful for functions that can't be converted via the `IntoFunction` trait.
    // For example, this function doesn't implement `IntoFunction` due to the fact that
    // the lifetime of the return value is not tied to the lifetime of the first argument.
    fn get_or_insert(value: i32, container: &mut Option<i32>) -> &i32 {
        if container.is_none() {
            *container = Some(value);
        }

        container.as_ref().unwrap()
    }

    let get_or_insert_function = dbg!(DynamicFunction::new(
        |mut args: ArgList| -> FunctionResult {
            // The `ArgList` contains the arguments in the order they were pushed.
            // The `DynamicFunction` will validate that the list contains
            // exactly the number of arguments we expect.
            // We can retrieve them out in order (note that this modifies the `ArgList`):
            let value = args.take::<i32>()?;
            let container = args.take::<&mut Option<i32>>()?;

            // We could have also done the following to make use of type inference:
            // let value = args.take_owned()?;
            // let container = args.take_mut()?;

            Ok(Return::Ref(get_or_insert(value, container)))
        },
        // Functions can be either anonymous or named.
        // It's good practice, though, to try and name your functions whenever possible.
        // This makes it easier to debug and is also required for function registration.
        // We can either give it a custom name or use the function's type name as
        // derived from `std::any::type_name_of_val`.
        SignatureInfo::named(std::any::type_name_of_val(&get_or_insert))
            // We can always change the name if needed.
            // It's a good idea to also ensure that the name is unique,
            // such as by using its type name or by prefixing it with your crate name.
            .with_name("my_crate::get_or_insert")
            // Since our function takes arguments, we should provide that argument information.
            // This is used to validate arguments when calling the function.
            // And it aids consumers of the function with their own validation and debugging.
            // Arguments should be provided in the order they are defined in the function.
            .with_arg::<i32>("value")
            .with_arg::<&mut Option<i32>>("container")
            // We can provide return information as well.
            .with_return::<&i32>(),
    ));

    let mut container: Option<i32> = None;

    let args = dbg!(ArgList::new().with_owned(5_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));

    let args = dbg!(ArgList::new().with_owned(500_i32).with_mut(&mut container));
    let value = dbg!(get_or_insert_function.call(args).unwrap()).unwrap_ref();
    assert_eq!(value.try_downcast_ref::<i32>(), Some(&5));
}

pub fn with_return_info(self, return_info: ReturnInfo) -> SignatureInfo

Set the return information of the function.

This will completely replace any existing return information.

For a simpler, static version of this method, see Self::with_return.

pub fn name(&self) -> Option<&Cow<'static, str>>

The name of the function.

For DynamicFunctions created using IntoFunction or DynamicFunctionMuts created using IntoFunctionMut, the default name will always be the full path to the function as returned by core::any::type_name, unless the function is a closure, anonymous function, or function pointer, in which case the name will be None.

pub fn args(&self) -> &[ArgInfo]

The arguments of the function.

pub fn arg_count(&self) -> usize

The number of arguments the function takes.

pub fn return_info(&self) -> &ReturnInfo

The return information of the function.

Trait Implementations

impl Clone for SignatureInfo

fn clone(&self) -> SignatureInfo

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SignatureInfo

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl TryFrom<SignatureInfo> for FunctionInfo

type Error = ArgCountOutOfBoundsError

The type returned in the event of a conversion error.

fn try_from( signature: SignatureInfo, ) -> Result<FunctionInfo, <FunctionInfo as TryFrom<SignatureInfo>>::Error>

Performs the conversion.