TypeStruct

Imitating static typed struct.

All type is checked by === method.

Usage

Check type

Sample = TypeStruct.new(
  str: String,
  reg: /exp/,
  num: Integer,
  any: Object,
)

sample = Sample.new(
  str: "instance of String",
  reg: "match to regexp",
  num: 10,
  any: true,
)

p sample
#=> #<Sample str="instance of String", reg="not match to regexp", num=10, any=true>

p sample.to_h
#=> {:str=>"instance of String", :reg=>"not match to regexp", :num=>10, :any=>true}

p sample.str
#=> "instance of String"

sample.string #=> NoMethodError
sample.str = 1 #=> TypeError

Mapping from Hash

Generate object from hash recursive

Point = TypeStruct.new(
  x: Integer,
  y: Integer,
)
Color = Struct.new(:code)
Line = TypeStruct.new(
  start: Point,
  end: Point,
  color: Color,
)

hash = JSON.parse(%({"start":{"x":3,"y":10},"end":{"x":5,"y":9},"color":{"code":"#CAFE00"}}))
line = Line.from_hash(hash)

p line
#=> #<Line start=#<Point x=3, y=10>, end=#<Point x=5, y=9>, color=#<struct Color code="#CAFE00">>
p line.start.y
#=> 10
line.stort
#=> NoMethodError

Four special notation

Union

Union is a object express class that some classes as one class like crystal Union.

Union#=== check all object with === method.

Foo = TypeStruct.new(
  bar: TypeStruct::Union.new(TrueClass, FalseClass)
)
p Foo.new(bar: false) #=> #<Foo bar=false>

or add Class#| method by refinements

require "type_struct/ext"
using TypeStruct::Union::Ext
Foo = TypeStruct.new(
  bar: TrueClass | FalseClass,
)

ArrayOf

ArrayOf is a object express array type.

ArrayOf#=== check all item with === method.

Bar = TypeStruct.new(
  baz: TypeStruct::ArrayOf.new(Integer),
)
p Bar.new(baz: [1, 2, 3]) #=> #<Bar baz=[1, 2, 3]>

HashOf

HashOf#=== check all keys and values with === method.

Baz = TypeStruct.new(
  qux: TypeStruct::HashOf.new(String, TypeStruct::ArrayOf.new(Integer))
)
p Baz.new(qux: { "a" => [1, 2, 3] }) #=> #<Baz qux={"a"=>[1, 2, 3]}>
p Baz.from_hash(qux: { "a" => [1, 2, 3] }) #<Baz qux={"a"=>[1, 2, 3]}>
p Baz.new(qux: { :a  => [1, 2, 3] }) #=> TypeError
p Baz.new(qux: { "a" => [1, 2, nil] }) #=> TypeError

Interface

Interface is a object for duck typing like golang interface.

Interface#=== check all method using respond_to?

Foo = TypeStruct.new(
  bar: TypeStruct::Interface.new(:read, :write)
  # or Interface.new(:read, :write) on required 'type_struct/ext'
)
Foo.new(bar: $stdin)
Foo.new(bar: 1) #=> TypeError

Mix

require "type_struct/ext"
using TypeStruct::Union::Ext
Baz = TypeStruct.new(
  qux: ArrayOf(Integer | TrueClass | FalseClass) | NilClass
)
p Baz.new(qux: [1]) #=> #<AAA::Baz qux=[1]>
p Baz.new(qux: [true, false]) #=> #<AAA::Baz qux=[true, false]>
p Baz.new(qux: nil) #=> #<AAA::Baz qux=nil>
p Baz.new(qux: 1) #=> TypeError
p Baz.from_hash(qux: [1, 2, false, true]) #=> #<A::Baz qux=[1, 2, false, true]>

Installation

Add this line to your application's Gemfile:

gem 'type_struct'

And then execute:

$ bundle

Or install it yourself as:

$ gem install type_struct

License

The gem is available as open source under the terms of the MIT License.