Optional

Optional

Optional represents the type of a value that might exist.

Specifications

Type	Size	Memory Management Model	File
Optional	? bytes	Scoped	2.7/Optional.adept

Definition

struct <$T> Optional (value $T, has bool)

where

$T is any valid type

Fields

Name	Type	Description
has	bool	Whether a value exists
value	$T	Wrapped value, only exists if has is true

Value Management Definitions

• verbatim func __defer__(this *<$T> Optional)
• func __assign__(this *<$T> Optional, other <$T> Optional)

Memory Management

optional.value is freed at the end of the scope if optional.has is true.

Functions

• func none() <$T> Optional

  Returns an empty optional. Should be used with ~> operator like none() ~> <int> Optional.

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• func some(contained POD $T) <$T> Optional

  Returns an optional with a contained value. The contained value is copied byte for byte, so some values may need modifications before being given to this function.

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Methods

• func set(this *<$T> Optional, value POD $T) void

  Sets an optional to a value. The value is copied byte for byte, so some values may need modifications before being given to this function.

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• func get(this *<$T> Optional) $T

  Gets the contained value of an optional.

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• func getPointer(this *<$T> Optional) *$T

  Gets a pointer to the contained value of an optional.

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• func rid(this *<$T> Optional) void

  Sets an optional to not contain anything.

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• func assign(this *<$T> Optional, value POD $T) void

  Destroys and clears the internal value of an optional, and then stores the new value using standard assignment semantics

  this.value.__defer__()
  memset(&this.value, 0, sizeof(this.value))
  this.value = value
  this.has = true
  

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• func assignPOD(this *<$T> Optional, value POD $T) void

  Destroys and clears the internal value of an optional, and then stores the new value using POD assignment semantics

  this.value.__defer__()
  memset(&this.value, 0, sizeof(this.value))
  this.value = POD value
  this.has = true
  

  [view src]

Undocumented Functions

These functions are undocumented as they are likely to change in the future.

• func isSome(this *<$T> Optional, out captured *$T) bool
• func map(this *<$T> Optional, function func($~T) $S) <$S> Optional
• func mapPOD(this *<$T> Optional, function func($~T) $S) <$S> Optional
• func pass(this *<$T> Optional) <$T> Optional

Disallowed functions

• func toString(_ <$T> Optional) String = delete {}

  Since it cannot be known whether we are responsible for freeing _.value, this call makes no sense

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Settings

#default Optional_error_no_value true