Detailed explanation of Mojo Optional and related interface description

Optional

Define Optional, a type that models values ​​that may or may not exist.

Optional values ​​can be considered type-safe as null mode. Your value can be valued orNone, you need to check and explicitly extract the value to remove it.

from  import Optional
var a = Optional(1)
var b = Optional[Int](None)
if a:
    print(())  # prints 1
if b:  # b is False, so no print
    print(())
var c = a.or_else(2)
var d = b.or_else(2)
print(())  # prints 1
print(())  # prints 2

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Optional

A type that models values ​​that may or may not exist.

Optional values ​​can be considered type-safe as null mode. Your value can be valued orNone, you need to check and explicitly extract the value to remove it.

Currently T needs to be aCollectionElement, so that we can implement Optional copy/move and allow it to be used in the collection itself.

from  import Optional
var a = Optional(1)
var b = Optional[Int](None)
if a:
    print(())  # prints 1
if b:  # b is False, so no print
    print(())
var c = a.or_else(2)
var d = b.or_else(2)
print(())  # prints 1
print(())  # prints 2

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parameter:

• T (CollectionElement): Stored in Optional.

Implementation features:

AnyType, Boolable, CollectionElement, Copyable, Movable

method:

__init__

__init__(inout self: Self)

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Construct an empty Optional.

__init__(inout self: Self, owned value: T)

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Constructs an Optional containing values.

parameter:

• value (T): The value to be stored in optional.

__init__(inout self: Self, value: None)

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Construct an empty Optional.

parameter:

• value (None): It must be exactlyNone 。

__bool__

__bool__(self: Self) -> Bool

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Returns true if Optional has a value.

return:

If the optional value is True, otherwise it is False.

__invert__

__invert__(self: Self) -> Bool

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Returns False if the optional has a value.

return:

True if the optional value is False, otherwise True.

Mojo Chinese website: Mojo Dev community:

__and__

__and__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has one value and the other value is forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if the Boolean forces the last two inputs to be True.

__or__

__or__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has a value or other value forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if either input is True after Boolean force.

__rand__

__rand__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has one value and the other value is forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if the Boolean forces the last two inputs to be True.

__ror__

__ror__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has a value or other value forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if either input is True after Boolean force.

value

value(self: Self) -> T

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Retrieve values ​​from "Optional" insecurely.

thisfunctionThe copy is currently created. Once we have life we ​​will be able to let it return a reference.

This does not check if the optional contains values. If you don't use it firstbool() Verify that optionally calls it for example. Whether you know it contains a value (e.g.if my_option:,useor_else) and you will get the junkUnsafedata.

return:

Option data contained in the form of a T value.

take

take(owned self: Self) -> T

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Unsafely moves the value out of "Optional".

The caller has ownership of the new value, and the optional value is Destroy.

This does not check if the optional contains values. If you don't use it firstbool() Verify that optionally calls it for example. Whether you know it contains a value (e.g.if my_option:,useor_else), you will get garbage unsafe data.

return:

The option contains data as the T value owned.

or_else

or_else(self: Self, default: T) -> T

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Returns the base value contained in Optional. If the base value of Optional does not exist, it returnsdefault value。

parameter:

• default (T): The new value to use when there is no value.

return:

The base value contained in "optional" or default values.

OptionalReg

registerA passable optional type.

This structure (optional) contains a value. It only works with trivial registers currently available types.

parameter:

• T (AnyRegType): Stored in Optional.

Implementation features:

AnyType, Boolable

method:

__init__

__init__() -> Self

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Create an option without a value.

return:

Optional.

__init__(value: T) -> Self

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Create an optional option with a value.

parameter:

• value (T):value.

return:

Optional.

__init__(value: None) -> Self

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Creates an option without the None text value.

parameter:

• value (None): No value.

return:

Optional without values.

__bool__

__bool__(self: Self) -> Bool

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Returns true if optional has a value.

return:

True if the optional option has vau, otherwise False.

__invert__

__invert__(self: Self) -> Bool

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Returns False if the optional has a value.

return:

True if the optional value is False, otherwise True.

__and__

__and__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has one value and the other value is forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if the Boolean forces the last two inputs to be True.

__or__

__or__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has a value or other value forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if either input is True after Boolean force.

__rand__

__rand__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has one value and the other value is forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if the Boolean forces the last two inputs to be True.

__ror__

__ror__[type: Boolable](self: Self, *other: "type") -> Bool

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Returns true if self has a value or other value forced to True.

parameter:

• type (Boolable): The type that is forced to Bool.

parameter:

• other (*"type"): The value to be compared.

return:

True if either input is True after Boolean force.

value

value(self: Self) -> T

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Gets optional values.

return:

The value contained.