Trait TypePath

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pub trait TypePath: 'static {
    // Required methods
    fn type_path() -> &'static str;
    fn short_type_path() -> &'static str;

    // Provided methods
    fn type_ident() -> Option<&'static str> { ... }
    fn crate_name() -> Option<&'static str> { ... }
    fn module_path() -> Option<&'static str> { ... }
}

Expand description

A static accessor to type paths and names.

The engine uses this trait over std::any::type_name for stability and flexibility.

This trait is automatically implemented by the #[derive(Reflect)] macro and allows type path information to be processed without an instance of that type.

Implementors may have difficulty in generating references with static lifetimes. Luckily, this crate comes with some utility structs, to make generating these statics much simpler.

§Stability

Certain parts of the engine, e.g. (de)serialization, rely on type paths as identifiers for matching dynamic values to concrete types.

Using std::any::type_name, a scene containing my_crate::foo::MyComponent would break, failing to deserialize if the component was moved from the foo module to the bar module, becoming my_crate::bar::MyComponent. This trait, through attributes when deriving itself or Reflect, can ensure breaking changes are avoidable.

The only external factor we rely on for stability when deriving is the module_path! macro, only if the derive does not provide a #[type_path = "..."] attribute.

§Anonymity

Some methods on this trait return Option<&'static str> over &'static str because not all types define all parts of a type path, for example the array type [T; N].

Such types are ‘anonymous’ in that they have only a defined type_path and short_type_path and the methods crate_name, module_path and type_ident all return None.

Primitives are treated like anonymous types, except they also have a defined type_ident.

§Example

use bevy_reflect::TypePath;

// This type path will not change with compiler versions or recompiles,
// although it will not be the same if the definition is moved.
#[derive(TypePath)]
struct NonStableTypePath;

// This type path will never change, even if the definition is moved.
#[derive(TypePath)]
#[type_path = "my_crate::foo"]
struct StableTypePath;

// Type paths can have any number of path segments.
#[derive(TypePath)]
#[type_path = "my_crate::foo::bar::baz"]
struct DeeplyNestedStableTypePath;

// Including just a crate name!
#[derive(TypePath)]
#[type_path = "my_crate"]
struct ShallowStableTypePath;

// We can also rename the identifier/name of types.
#[derive(TypePath)]
#[type_path = "my_crate::foo"]
#[type_name = "RenamedStableTypePath"]
struct NamedStableTypePath;

// Generics are also supported.
#[derive(TypePath)]
#[type_path = "my_crate::foo"]
struct StableGenericTypePath<T, const N: usize>([T; N]);

Required Methods§

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fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

Generic parameter types are also fully expanded.

For Option<Vec<usize>>, this is "std::option::Option<std::vec::Vec<usize>>".

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fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type.

Generic parameter types are also shortened.

For Option<Vec<usize>>, this is "Option<Vec<usize>>".

Provided Methods§

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fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous.

Primitive types will return Some.

For Option<Vec<usize>>, this is "Option".

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fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous.

For Option<Vec<usize>>, this is "core".

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fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous.

For Option<Vec<usize>>, this is "std::option".

Object Safety§

This trait is not object safe.

Trait TypePathCopy item path

§Stability

§Anonymity

§Example

Required Methods§

fn type_path() -> &'static str

fn short_type_path() -> &'static str

Provided Methods§

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

Object Safety§

Implementations on Foreign Types§

impl TypePath for boolwhere bool: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for charwhere char: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for f32where f32: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for f64where f64: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for i8where i8: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for i16where i16: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for i32where i32: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for i64where i64: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for i128where i128: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for isizewhere isize: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for strwhere str: Any + Send + Sync,

fn type_path() -> &'static str

fn short_type_path() -> &'static str

fn type_ident() -> Option<&'static str>

fn crate_name() -> Option<&'static str>

fn module_path() -> Option<&'static str>

impl TypePath for u8where u8: Any + Send + Sync,

Trait TypePath

impl TypePath for bool
where bool: Any + Send + Sync,

impl TypePath for char
where char: Any + Send + Sync,

impl TypePath for f32
where f32: Any + Send + Sync,

impl TypePath for f64
where f64: Any + Send + Sync,

impl TypePath for i8
where i8: Any + Send + Sync,

impl TypePath for i16
where i16: Any + Send + Sync,

impl TypePath for i32
where i32: Any + Send + Sync,

impl TypePath for i64
where i64: Any + Send + Sync,

impl TypePath for i128
where i128: Any + Send + Sync,

impl TypePath for isize
where isize: Any + Send + Sync,

impl TypePath for str
where str: Any + Send + Sync,

impl TypePath for u8
where u8: Any + Send + Sync,

impl TypePath for u16
where u16: Any + Send + Sync,

impl TypePath for u32
where u32: Any + Send + Sync,

impl TypePath for u64
where u64: Any + Send + Sync,

impl TypePath for u128
where u128: Any + Send + Sync,

impl TypePath for usize
where usize: Any + Send + Sync,

impl TypePath for SmolStr
where SmolStr: Any + Send + Sync,

impl TypePath for String
where String: Any + Send + Sync,

impl TypePath for TypeId
where TypeId: Any + Send + Sync,

impl TypePath for BuildHasherDefault<AHasher>
where BuildHasherDefault<AHasher>: Any + Send + Sync,