TypeStruct
Imitating static typed struct.
All type is checked by === method.
Motivation
I don't like Hash
p h #=> {color: 'red', width: 120, height: 200}No name
What is this a data? We cannot know this name.
Where is this an instance from? How do we grep doing?
Bad syntax
h[:widht] #=> Cannot detect typo
#=> nil
h.dig(:widht) #=> ditto
#=> nil
h.fetch(:widht) #=> Can detect typo, But too long and cannot know suggestion from did_you_mean gem
# KeyError: key not found: :widhtToo freedom
# Where is from `who` key? Is this expected?
p h #=> {color: 'red', width: 120, height: 200, who: 'are you?'}I like Struct
Grepable Name
Circle = Struct.new(:color, :width, :height)
circle = Circle.new('red', 120, 200)Good syntax
circle.color
#=> 'red'
circle.widht
# NoMethodError:
Did you mean? width
width=Strictly members
circle.who = "are you?"
# NoMethodError: undefined method `who='Evolution
- Can use keyword arguments
- Add Type system
- Recursive Mapping
This is the TypeStruct.
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 #=> TypeErrorRecursive Mapping
Generate object from hash by recursive.
Like JSON package of golang and crystal-lang.
Point = TypeStruct.new(
x: Integer,
y: Integer,
)
Color = TypeStruct.new(
code: /\A#[0-9a-f]{6}\z/i,
)
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=#<Color code="#CAFE00">>
p line.start.y
#=> 10
line.stort
#=> NoMethodErrorFour special classes
Union
Union is an 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 an 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] }) #=> TypeErrorInterface
Interface is an 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) #=> TypeErrorMix
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]>Auto Generator
$ echo '{"posts": [{"number":10491,"name":"ksss"}]}' | ruby -r type_struct/generator/json
Post = TypeStruct.new(
number: Integer,
name: String,
)
AutoGeneratedStruct = TypeStruct.new(
posts: ArrayOf(Post),
)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.