struct Union(*T)
Overview
A union type represents the possibility of a variable or an expression having more than one possible type at compile time.
When invoking a method on a union type, the language checks that the
method exists and can be resolved (typed) for each type in the union.
For this reason, adding instance methods to Union
makes no sense and
has no effect. However, adding class method to Union
is possible
and can be useful. One example is parsing JSON
into one of many
possible types.
Union is special in that it is a generic type but instantiating it might not return a union type:
Union(Int32 | String) # => (Int32 | String)
Union(Int32) # => Int32
Union(Int32, Int32, Int32) # => Int32
Defined in:
union.crConstructors
Class Method Summary
Instance methods inherited from struct Value
==(other)
==,
dup
dup
Instance methods inherited from class Object
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, tap(&block) tap, to_json(io : IO)
to_json to_json, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ") to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&block) try, unsafe_as(type : T.class) forall T unsafe_as
Constructor methods inherited from class Object
from_json(string_or_io, root : String) : selffrom_json(string_or_io) : self from_json, from_yaml(string_or_io) : self from_yaml