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(r : Reference?) : Pointer(Void)
Creates a Box for a reference type (or
nil
) and returns the same pointer (orNULL
) - .box(object) : Pointer(Void)
Creates a Box for an object and returns it as 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, 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 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! 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
def self.new(object : T)Source
Class Method Detail
def self.box(r : Reference?) : Pointer(Void)Source
Creates a Box for a reference type (or nil
) and returns the same pointer (or NULL
)
def self.unbox(pointer : Pointer(Void)) : TSource
Unboxes a Void*
into an object of type T
. Note that for this you must specify T: Box(T).unbox(data)
.
Instance Method Detail
def object : TSource
Returns the original object
© 2012–2021 Manas Technology Solutions.
Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/1.2.1/Box.html