Struct MaybeLocation

pub struct MaybeLocation<T: ?Sized = &'static Location<'static>> { /* private fields */ }

A value that contains a T if the track_location feature is enabled, and is a ZST if it is not.

The overall API is similar to Option, but whether the value is Some or None is set at compile time and is the same for all values.

If the track_location feature is disabled, then all functions on this type that return an MaybeLocation will have an empty body and should be removed by the optimizer.

This allows code to be written that will be checked by the compiler even when the feature is disabled, but that will be entirely removed during compilation.

Implementations

impl<T> MaybeLocation<T>

pub const fn new(_value: T) -> Self

where T: Copy,

Constructs a new MaybeLocation that wraps the given value.

This may only accept Copy types, since it needs to drop the value if the track_location feature is disabled, and non-Copy types cannot be dropped in const context. Use new_with if you need to construct a non-Copy value.

See also

• new_with to initialize using a closure.
• new_with_flattened to initialize using a closure that returns an Option<MaybeLocation<T>>.

pub fn new_with(_f: impl FnOnce() -> T) -> Self

Constructs a new MaybeLocation that wraps the result of the given closure.

See also

• new to initialize using a value.
• new_with_flattened to initialize using a closure that returns an Option<MaybeLocation<T>>.

pub fn map<U>(self, _f: impl FnOnce(T) -> U) -> MaybeLocation<U>

Maps an MaybeLocation<T> to MaybeLocation<U> by applying a function to a contained value.

pub fn zip<U>(self, _other: MaybeLocation<U>) -> MaybeLocation<(T, U)>

Converts a pair of MaybeLocation values to an MaybeLocation of a tuple.

pub fn unwrap_or_default(self) -> T

where T: Default,

Returns the contained value or a default. If the track_location feature is enabled, this always returns the contained value. If it is disabled, this always returns T::Default().

pub fn into_option(self) -> Option<T>

Converts an MaybeLocation to an Option to allow run-time branching. If the track_location feature is enabled, this always returns Some. If it is disabled, this always returns None.

impl<T> MaybeLocation<Option<T>>

pub fn new_with_flattened(_f: impl FnOnce() -> Option<MaybeLocation<T>>) -> Self

Constructs a new MaybeLocation that wraps the result of the given closure. If the closure returns Some, it unwraps the inner value.

See also

• new to initialize using a value.
• new_with to initialize using a closure.

pub fn transpose(self) -> Option<MaybeLocation<T>>

Transposes a MaybeLocation of an Option into an Option of a MaybeLocation.

This can be useful if you want to use the ? operator to exit early if the track_location feature is enabled but the value is not found.

If the track_location feature is enabled, this returns Some if the inner value is Some and None if the inner value is None.

If it is disabled, this always returns Some.

Example

let mut world = World::new();
let entity = world.spawn(()).id();
let location: MaybeLocation<Option<&'static Location<'static>>> =
    world.entities().entity_get_spawned_or_despawned_by(entity);
let location: MaybeLocation<&'static Location<'static>> = location.transpose()?;

See also

• into_option to convert to an Option<Option<T>>. When used with Option::flatten, this will have a similar effect, but will return None when the track_location feature is disabled.

impl<T> MaybeLocation<&T>

pub const fn copied(&self) -> MaybeLocation<T>

where T: Copy,

Maps an MaybeLocation<&T> to an MaybeLocation<T> by copying the contents.

impl<T> MaybeLocation<&mut T>

pub const fn copied(&self) -> MaybeLocation<T>

where T: Copy,

Maps an MaybeLocation<&mut T> to an MaybeLocation<T> by copying the contents.

pub fn assign(&mut self, _value: MaybeLocation<T>)

Assigns the contents of an MaybeLocation<T> to an MaybeLocation<&mut T>.

impl<T: ?Sized> MaybeLocation<T>

pub const fn as_ref(&self) -> MaybeLocation<&T>

Converts from &MaybeLocation<T> to MaybeLocation<&T>.

pub const fn as_mut(&mut self) -> MaybeLocation<&mut T>

Converts from &mut MaybeLocation<T> to MaybeLocation<&mut T>.

pub fn as_deref(&self) -> MaybeLocation<&T::Target>

where T: Deref,

Converts from &MaybeLocation<T> to MaybeLocation<&T::Target>.

pub fn as_deref_mut(&mut self) -> MaybeLocation<&mut T::Target>

where T: DerefMut,

Converts from &mut MaybeLocation<T> to MaybeLocation<&mut T::Target>.

impl MaybeLocation

pub fn caller() -> Self

Returns the source location of the caller of this function. If that function’s caller is annotated then its call location will be returned, and so on up the stack to the first call within a non-tracked function body.

Trait Implementations

impl<T: Clone + ?Sized> Clone for MaybeLocation<T>

fn clone(&self) -> MaybeLocation<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug + ?Sized> Debug for MaybeLocation<T>

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

Formats the value using the given formatter.

impl<T: Display> Display for MaybeLocation<T>

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

Formats the value using the given formatter.

impl<T> FromReflect for MaybeLocation<T>

where MaybeLocation<T>: Any + Send + Sync, T: TypePath + ?Sized,

fn from_reflect(reflect: &dyn PartialReflect) -> Option<Self>

Constructs a concrete instance of Self from a reflected value.

fn take_from_reflect( reflect: Box<dyn PartialReflect>, ) -> Result<Self, Box<dyn PartialReflect>>

Attempts to downcast the given value to Self using, constructing the value using from_reflect if that fails.

impl<T> GetTypeRegistration for MaybeLocation<T>

where MaybeLocation<T>: Any + Send + Sync, T: TypePath + ?Sized,

fn get_type_registration() -> TypeRegistration

Returns the default TypeRegistration for this type.

fn register_type_dependencies(registry: &mut TypeRegistry)

Registers other types needed by this type.

impl<T: Hash + ?Sized> Hash for MaybeLocation<T>

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T: Ord + ?Sized> Ord for MaybeLocation<T>

fn cmp(&self, other: &MaybeLocation<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T: PartialEq + ?Sized> PartialEq for MaybeLocation<T>

fn eq(&self, other: &MaybeLocation<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: PartialOrd + ?Sized> PartialOrd for MaybeLocation<T>

fn partial_cmp(&self, other: &MaybeLocation<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T> PartialReflect for MaybeLocation<T>

where MaybeLocation<T>: Any + Send + Sync, T: TypePath + ?Sized,

fn get_represented_type_info(&self) -> Option<&'static TypeInfo>

Returns the TypeInfo of the type represented by this value.

fn try_apply(&mut self, value: &dyn PartialReflect) -> Result<(), ApplyError>

Tries to apply a reflected value to this value.

fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type.

fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type.

fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type.

fn reflect_owned(self: Box<Self>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type.

fn try_into_reflect( self: Box<Self>, ) -> Result<Box<dyn Reflect>, Box<dyn PartialReflect>>

Attempts to cast this type to a boxed, fully-reflected value.

fn try_as_reflect(&self) -> Option<&dyn Reflect>

Attempts to cast this type to a fully-reflected value.

fn try_as_reflect_mut(&mut self) -> Option<&mut dyn Reflect>

Attempts to cast this type to a mutable, fully-reflected value.

fn into_partial_reflect(self: Box<Self>) -> Box<dyn PartialReflect>

Casts this type to a boxed, reflected value.

fn as_partial_reflect(&self) -> &dyn PartialReflect

Casts this type to a reflected value.

fn as_partial_reflect_mut(&mut self) -> &mut dyn PartialReflect

Casts this type to a mutable, reflected value.

fn reflect_partial_eq(&self, value: &dyn PartialReflect) -> Option<bool>

Returns a “partial equality” comparison result.

fn reflect_clone(&self) -> Result<Box<dyn Reflect>, ReflectCloneError>

Attempts to clone Self using reflection.

fn apply(&mut self, value: &(dyn PartialReflect + 'static))

Applies a reflected value to this value.

fn clone_value(&self) -> Box<dyn PartialReflect>

👎Deprecated since 0.16.0: to clone reflected values, prefer using reflect_clone. To convert reflected values to dynamic ones, use to_dynamic.

Clones Self into its dynamic representation.

fn to_dynamic(&self) -> Box<dyn PartialReflect>

Converts this reflected value into its dynamic representation based on its kind.

fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type).

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

Debug formatter for the value.

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl<T> Reflect for MaybeLocation<T>

where MaybeLocation<T>: Any + Send + Sync, T: TypePath + ?Sized,

fn into_any(self: Box<Self>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &dyn Any

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut dyn Any

Returns the value as a &mut dyn Any.

fn into_reflect(self: Box<Self>) -> Box<dyn Reflect>

Casts this type to a boxed, fully-reflected value.

fn as_reflect(&self) -> &dyn Reflect

Casts this type to a fully-reflected value.

fn as_reflect_mut(&mut self) -> &mut dyn Reflect

Casts this type to a mutable, fully-reflected value.

fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value.

impl<T> Struct for MaybeLocation<T>

where MaybeLocation<T>: Any + Send + Sync, T: TypePath + ?Sized,

fn field(&self, name: &str) -> Option<&dyn PartialReflect>

Returns a reference to the value of the field named name as a &dyn PartialReflect.

fn field_mut(&mut self, name: &str) -> Option<&mut dyn PartialReflect>

Returns a mutable reference to the value of the field named name as a &mut dyn PartialReflect.

fn field_at(&self, index: usize) -> Option<&dyn PartialReflect>

Returns a reference to the value of the field with index index as a &dyn PartialReflect.

fn field_at_mut(&mut self, index: usize) -> Option<&mut dyn PartialReflect>

Returns a mutable reference to the value of the field with index index as a &mut dyn PartialReflect.

fn name_at(&self, index: usize) -> Option<&str>

Returns the name of the field with index index.

fn field_len(&self) -> usize

Returns the number of fields in the struct.

fn iter_fields(&self) -> FieldIter<'_>

Returns an iterator over the values of the reflectable fields for this struct.

fn to_dynamic_struct(&self) -> DynamicStruct

fn clone_dynamic(&self) -> DynamicStruct

👎Deprecated since 0.16.0: use to_dynamic_struct instead

Clones the struct into a DynamicStruct.

fn get_represented_struct_info(&self) -> Option<&'static StructInfo>

Will return None if TypeInfo is not available.

impl<T> TypePath for MaybeLocation<T>

where MaybeLocation<T>: Any + Send + Sync, T: TypePath + ?Sized,

fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

fn short_type_path() -> &'static str

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

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

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

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

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

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

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

impl<T> Typed for MaybeLocation<T>

where MaybeLocation<T>: Any + Send + Sync, T: TypePath + ?Sized,

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.

impl<T: Copy + ?Sized> Copy for MaybeLocation<T>

impl<T: Eq + ?Sized> Eq for MaybeLocation<T>

impl<T: ?Sized> StructuralPartialEq for MaybeLocation<T>