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Mojo struct

UnsafeMaybeUninitialized

struct UnsafeMaybeUninitialized[ElementType: AnyType]

A memory location that may or may not be initialized.

Note that the destructor is a no-op. If the memory was initialized, the caller is responsible for calling assume_initialized_destroy before the memory is deallocated.

Every method in this struct is unsafe and the caller must know at all times if the memory is initialized or not. Calling a method that assumes the memory is initialized when it is not will result in undefined behavior.

Parameters​

  • ​ElementType (AnyType): The type of the element to store.

Aliases​

  • type = array<1, :trait<@stdlib::@builtin::@anytype::@AnyType> ElementType>:

Implemented traits​

AnyType, CollectionElement, CollectionElementNew, Copyable, ExplicitlyCopyable, Movable, UnknownDestructibility

Methods​

__init__​

__init__(out self)

The memory is now considered uninitialized.

__init__[MovableType: Movable](out self: UnsafeMaybeUninitialized[MovableType], owned value: MovableType)

The memory is now considered initialized.

Parameters:

  • ​MovableType (Movable): The type of the element to store.

Args:

  • ​value (MovableType): The value to initialize the memory with.

__copyinit__​

__copyinit__(out self, other: Self)

Copy another object.

This method should never be called as implicit copy should not be done on memory that may be uninitialized.

Trying to call this method will abort.

If you wish to perform a copy, you should manually call the method copy_from instead.

Args:

  • ​other (Self): The object to copy.

__moveinit__​

__moveinit__(out self, owned other: Self)

Move another object.

This method should never be called as implicit moves should not be done on memory that may be uninitialized.

Trying to call this method will abort.

If you wish to perform a move, you should manually call the method move_from instead.

Args:

  • ​other (Self): The object to move.

__del__​

__del__(owned self)

This is a no-op.

Calling this method assumes that the memory is uninitialized. If the memory was initialized, the caller should use assume_initialized_destroy before.

copy_from​

copy_from[CopyableType: ExplicitlyCopyable](mut self: UnsafeMaybeUninitialized[CopyableType], other: UnsafeMaybeUninitialized[CopyableType])

Copy another object.

This function assumes that the current memory is uninitialized and the other object is initialized memory.

Parameters:

  • ​CopyableType (ExplicitlyCopyable): The type object to copy.

Args:

  • ​other (UnsafeMaybeUninitialized[CopyableType]): The object to copy.

copy_from[CopyableType: ExplicitlyCopyable](mut self: UnsafeMaybeUninitialized[CopyableType], other: CopyableType)

Copy another object.

This function assumes that the current memory is uninitialized.

Parameters:

  • ​CopyableType (ExplicitlyCopyable): The type object to copy.

Args:

  • ​other (CopyableType): The object to copy.

move_from​

move_from[MovableType: Movable](mut self: UnsafeMaybeUninitialized[MovableType], mut other: UnsafeMaybeUninitialized[MovableType])

Move another object.

This function assumes that the current memory is uninitialized and the other object is initialized memory.

After the function is called, the other object is considered uninitialized.

Parameters:

  • ​MovableType (Movable): The type object to move.

Args:

  • ​other (UnsafeMaybeUninitialized[MovableType]): The object to move.

move_from[MovableType: Movable](mut self: UnsafeMaybeUninitialized[MovableType], other: UnsafePointer[MovableType])

Move another object.

This function assumes that the current memory is uninitialized and the other object is initialized memory.

After the function is called, the other object is considered uninitialized.

Parameters:

  • ​MovableType (Movable): The type object to move.

Args:

  • ​other (UnsafePointer[MovableType]): The pointer to the object to move.

write​

write[MovableType: Movable](mut self: UnsafeMaybeUninitialized[MovableType], owned value: MovableType)

Write a value into an uninitialized memory location.

Calling this method assumes that the memory is uninitialized.

Parameters:

  • ​MovableType (Movable): The type of the element to store.

Args:

  • ​value (MovableType): The value to write.

assume_initialized​

assume_initialized(ref self) -> ref [self] ElementType

Returns a reference to the internal value.

Calling this method assumes that the memory is initialized.

Returns:

A reference to the internal value.

unsafe_ptr​

unsafe_ptr(self) -> UnsafePointer[ElementType]

Get a pointer to the underlying element.

Note that this method does not assumes that the memory is initialized or not. It can always be called.

Returns:

A pointer to the underlying element.

assume_initialized_destroy​

assume_initialized_destroy(mut self)

Runs the destructor of the internal value.

Calling this method assumes that the memory is initialized.