philiprehberger-struct_kit

Enhanced struct builder with typed fields, defaults, validation, and pattern matching

Requirements

Ruby >= 3.1

Installation

Add to your Gemfile:

gem "philiprehberger-struct_kit"

Or install directly:

gem install philiprehberger-struct_kit

Usage

require "philiprehberger/struct_kit"

User = Philiprehberger::StructKit.define do
  field :name, String
  field :age, Integer, default: 0
  field :role, Symbol, default: :user
  validate :age, range: 0..150
end

user = User.new(name: 'Alice', age: 30)
user.name   # => "Alice"
user.age    # => 30
user.frozen? # => true

Type Checking

Point = Philiprehberger::StructKit.define do
  field :x, Integer
  field :y, Integer
  field :active, [TrueClass, FalseClass], default: true
end

Point.new(x: 1, y: 2)            # OK
Point.new(x: 'a', y: 2)          # TypeError!
Point.new(x: 1, y: 2, active: 0) # TypeError!

Default Values

Config = Philiprehberger::StructKit.define do
  field :timeout, Integer, default: 30
  field :tags, Array, default: -> { [] }  # lambda for mutable defaults
end

Validation

Email = Philiprehberger::StructKit.define do
  field :address, String
  validate :address, format: /@/
end

Mutable Structs

MutableUser = Philiprehberger::StructKit.define(mutable: true) do
  field :name, String
  field :age, Integer, default: 0
end

user = MutableUser.new(name: 'Alice')
user.name = 'Bob'  # OK, not frozen

Serialization

user = User.new(name: 'Alice', age: 30)

user.to_h    # => { name: "Alice", age: 30, role: :user }
user.to_json # => '{"name":"Alice","age":30,"role":"user"}'

User.from_h({ 'name' => 'Bob', 'age' => 25 })  # string keys OK

Pattern Matching

case user
in { role: :admin }
  puts 'Admin user'
in { role: :user }
  puts 'Regular user'
end

API

`Philiprehberger::StructKit.define(mutable: false, &block)`

Define a new struct class. Evaluates the block in DSL context.

DSL Methods

Method	Description
`field(name, type = nil, default: UNSET)`	Declare a typed field with optional default
`validate(name, range: nil, format: nil, &block)`	Add validation rule to a field

Instance Methods

Method	Description
`#to_h`	Convert to a plain hash
`#to_json`	Convert to JSON string
`#deconstruct_keys(keys)`	Pattern matching support
`#==`	Value equality
`#inspect`	Human-readable string representation

Class Methods

Method	Description
`.from_h(hash)`	Construct from hash (string or symbol keys)

Development

bundle install
bundle exec rspec
bundle exec rubocop

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License

MIT