class Box(T)
Overview
A Box allows turning any object to a Void*
and back.
A Box's purpose is passing data to C as a Void*
and then converting that
back to the original data type.
For an example usage, see Proc
's explanation about sending Procs to C.
Defined in:
box.crConstructors
-
.new(object : T)
Creates a
Box
with the given object.
Class Method Summary
-
.box(object : T) : Pointer(Void)
Turns object into a
Void*
. -
.unbox(pointer : Pointer(Void)) : T
Unboxes a
Void*
into an object of typeT
.
Instance Method Summary
-
#object : T
Returns the original object
Instance methods inherited from class Reference
==(other : self)==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup, hash(hasher) hash, initialize initialize, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference) : Bool
same?(other : Nil) same?, to_s(io : IO) : Nil to_s
Constructor methods inherited from class Reference
new
new,
unsafe_construct(address : Pointer, *args, **opts) : self
unsafe_construct
Class methods inherited from class Reference
pre_initialize(address : Pointer)
pre_initialize
Instance methods inherited from class Object
! : Bool
!,
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash hash, in?(collection : Object) : Bool
in?(*values : Object) : Bool in?, inspect(io : IO) : Nil
inspect : String inspect, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String to_json, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil to_pretty_json, to_s(io : IO) : Nil
to_s : String to_s, to_yaml(io : IO) : Nil
to_yaml : String to_yaml, try(&) try, unsafe_as(type : T.class) forall T unsafe_as
Class methods inherited from class Object
from_json(string_or_io, root : String)from_json(string_or_io) from_json, from_yaml(string_or_io : String | IO) from_yaml
Constructor Detail
Creates a Box
with the given object.
This method isn't usually used directly. Instead, Box.box
is used.
Class Method Detail
Turns object into a Void*
.
If T
is not a reference type, nor a union between reference types and
Nil
, this method effectively copies object to the dynamic heap.
NOTE The returned pointer might not be a null pointer even when object is
nil
.
Unboxes a Void*
into an object of type T
. Note that for this you must
specify T: Box(T).unbox(data)
.
WARNING It is undefined behavior to box an object in one type and unbox it
via a different type; in particular, when boxing a T
and unboxing it as a
T?
, or vice-versa.