Class: MethodFound::SimpleModel

Inherits:
Object
  • Object
show all
Defined in:
lib/method_found/simple_model.rb

Overview

Example class using MethodFound interceptors to implement attributes and change tracking. Symbols passed into constructor define patterns in interceptor modules to catch method calls and define methods on module as needed. New methods can be dynamically defined by calling any undefined method with a bang (!).

This class is not included by default when requiring MethodFound, so you will need to explicitly require it with:

require "method_found/simple_model"

Examples:

Setting Attributes

post = MethodFound::SimpleModel.new(:title, :content)

post.title = "Method Found"
post.content = "Once upon a time..."

post.title
#=> "Method Found"

post.content
#=> "Once upon a time..."

Dyanamically defining new attributes

post = MethodFound::SimpleModel.new

post.foo
#=> raises MethodNotFound error

post.foo!
#=> nil

post.foo = "my foo"
post.foo
#=> "my foo"

Tracking changes

post = MethodFound::SimpleModel.new(:title)

post.title = "foo"
post.title_changed?
#=> false

post.title = "bar"
post.title_changed?
#=> true
post.title_was
#=> "foo"
post.title_changes
#=> ["bar", "foo"]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*attribute_names) ⇒ SimpleModel

Returns a new instance of SimpleModel.

Parameters:

  • attribute_names (Symbol) —

    One or more attribute names to define interceptors for on model.



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# File 'lib/method_found/simple_model.rb', line 61

def initialize(*attribute_names)
  @attributes = Hash.new { |h, k| h[k] = [] }

  @attribute_builder = builder = Builder.new do
    def define_missing(attribute_name)
      intercept /\A(#{attribute_name})(=|\?)?\Z/.freeze do |_, matches, *arguments|
        name  = matches[1]
        value = @attributes[name].last

        if matches[2] == "=".freeze
          new_value = arguments[0]
          @attributes[name].push(new_value) unless new_value == value
        else
          matches[2] == "?".freeze ? !!value : value
        end
      end

      intercept /\A(reset_(#{attribute_name})|(#{attribute_name})_(changed\?|changes|was))\Z/.freeze do |_, matches|
        if matches[1] == "reset_#{attribute_name}".freeze
          !!@attributes.delete(matches[2])
        else
          changes = @attributes[matches[3]]
          if matches[4] == "changes".freeze
            changes.reverse
          elsif matches[4] == "was".freeze
            changes[-2]
          else
            changes.size > 1
          end
        end
      end
    end

    intercept /\A(.+)\!\Z/ do |_, matches|
      builder.define_missing matches[1]
      singleton_class.include builder
      @attributes[matches[1]].last
    end
  end
  attribute_names.each { |name| builder.define_missing(name) }

  singleton_class.include builder
end

Instance Attribute Details

#attribute_builder ⇒ Object (readonly)

Returns the value of attribute attribute_builder.



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# File 'lib/method_found/simple_model.rb', line 57

def attribute_builder
  @attribute_builder
end

Instance Method Details

#attributes ⇒ Object 



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# File 'lib/method_found/simple_model.rb', line 105

def attributes
  Hash[@attributes.map { |k, v| [k, v.last] }]
end