method_arguments gem

With the method_arguments gem you can easily set object attributes from method arguments.

Transform this:

  def initialize(user_entity, first_name:, last_name:, email:, phone:, dob:)
    @user_entity = user_entity
    @first_name = first_name
    @last_name = last_name
    @email = email
    @phone = phone
    @dob = dob
  end

into this streamlined version:

  def initialize(user_entity, first_name:, last_name:, email:, phone:, dob:)
    set_instance_vars(__method_args__)
  end

Features

1. Reading Method Arguments

Within any method, call __method_args__ to retrieve its arguments as a Hash.

  def initialize(user_entity, first_name:, last_name:, age:, **kw_rest)
    "Method ##{__method__} received #{__method_args__.inspect} arguments"
  end

Limitations

1. Argument types `*rest` and `**keyrest` are ignored regardless of their name: ```ruby def initialize(arg, *arg_rest, kw_arg:, **kw_rest) __method_args__ # returns { a: , kw_arg: } end ``` Casting unknown arbitrary arguments to instance variables is not recommended for security reasons. 2. The method does not support [argument forwarding](https://docs.ruby-lang.org/en/3.2/syntax/methods_rdoc.html#label-Argument+Forwarding): ```ruby def self.call(...) new(__method_args__).call # raises error end ```

2. Filling instance @variables

Use set_instance_vars(hash) to assign instance variables from a Hash.

3. Filling instance @variables using attribute writers

To leverage setters (attribute writers), add use_writers: true argument. If a writer with the corresponding name exists, it will be invoked.

Example

Before: ```ruby def initialize(user_entity, first_name:, last_name:, age:) @user_entity = user_entity @first_name = first_name @last_name = last_name self.age = age end def age=(val) @age = Integer(val) end ``` After: ```ruby def initialize(user_entity, first_name:, last_name:, age:, ...) set_instance_vars(__method_args__, use_writers: true) end def age=(val) @age = Integer(val) end ```

Installation

Add to your Gemfile, then run bundle install:
```
gem "method_arguments"
```
Prepend your code with
```
require "method_arguments"
```

Supported Ruby Versions

This gem is designed to be compatible with Ruby 2.7 and above. It has been tested on the following MRI versions:

v2.7.2
v3.0.3
v3.1.2

If you encounter any issues with later versions, please feel free to report them.