striuct

Struct++

Usage

Require Ruby 2.6 or later

Add this line to your Gemfile

gem 'striuct', '>= 0.8.0', '< 0.9.0'

Then add below code into your Ruby code

require 'striuct'

Overview

Case 1

require 'striuct'

class Person < Striuct
  member :full_name, AND(String, /\A.+\z/)     # Flexible Validation
  alias_member :name, :full_name               # Use other name
end

# Inheritable
class User < Person
  member :id, Integer,                        # Looks typed validation
              default_proc: ->{User.next_id}  # With default value

  @id = 0
  def self.next_id
    @id += 1
  end
end

john = User.new 'john'
john[:name]              #=> 'john'
john.name = ''           #=> Exception        # Validate with setter
john.id                  #=> 1
ken = User[name: 'ken']                       # Construct from hash
ken.id                   #=> 2

Case 2

class Foo < Striuct
  member :foo
  member :bar, Numeric
  member :with_adjuster, Integer,
                         &->v{Integer v}      # Use adjuster before a setter
end

foo = Foo.new

# nil <-> unassigned
foo.foo                  #=> nil
foo.assigned?(:foo)      #=> false
foo.foo = nil
foo.assigned?(:foo)      #=> true

# Lock to a member
foo.lock(:foo)
foo.foo = nil            #=> error

foo.bar = 1.2            #=> pass             # memorize 1.2's class is Float
foo.bar = 1              #=> error            # 1 is not Float

# With adjuster
foo.with_adjuster = '5'
foo.with_adjuster        #=> 5                # Casted via adjuster

Case 3

class UseMustOption < Striuct
  member :foo, Integer, must: true
end

UseMustOption.new #=> InvalidOperationError "`foo` require a value under `must` option "

Features

Strict

  • Easy and Flexible Validations

  • Basically use #=== for the validation

  • The pattern builder DSL is just using eqq

  • When passed the Proc, it will be evaluated in the instance context

  • Prevent to conflict member names

  • Lock setters for each member

Useful

  • Hook just before setters

  • Default value

  • Member aliasing

  • Inheritable

  • Handling between nil <-> unassigned

  • Similar API for Hash

Finally

  • Base API looks like Struct

  • Pure Ruby :)