Class: WhyClasses::Rules::StatelessSingletonMethods

Inherits:
WhyClasses::Rule show all
Defined in:
lib/why_classes/rules/stateless_singleton_methods.rb

Overview

Rule 3 (summary): "If it has no state, it should not be a class." A class whose body is only self. methods is a namespace for functions, not an object factory -- it should be a module.

Constant Summary

Constants inherited from WhyClasses::Rule

WhyClasses::Rule::H

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from WhyClasses::Rule

autocorrectable?, #call, inherited, #initialize, rule_name

Constructor Details

This class inherits a constructor from WhyClasses::Rule

Class Method Details

.description ⇒ Object 



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# File 'lib/why_classes/rules/stateless_singleton_methods.rb', line 12

def self.description
  "Class with only class methods and no state -> use a module with `extend self`."
end

.tier ⇒ Object 



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# File 'lib/why_classes/rules/stateless_singleton_methods.rb', line 16

def self.tier
  :unsafe
end

Instance Method Details

#on_class(node) ⇒ Object 



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# File 'lib/why_classes/rules/stateless_singleton_methods.rb', line 20

def on_class(node)
  s = shape(node)
  return if s.name.nil?
  return if s.superclass? # inheritance is a separate concern (see InheritanceForMixins)
  return if configuration.framework_base_class?(s.superclass)
  return unless only_singleton_methods?(s)

  corrector =
    if Correctors::StatelessModuleCorrector.correctable?(s)
      Correctors::StatelessModuleCorrector.corrector(node)
    end

  add_offense(
    node,
    message: "#{s.name} has only class methods and no state; it's a bucket of functions, " \
             "not an object factory.",
    suggestion: "Make it a module and expose the methods with `extend self`:\n" \
                "    module #{s.name}\n      def #{example_method(s)}(...)\n        ...\n      end\n\n" \
                "      private\n      # helper methods here are now genuinely private\n\n" \
                "      extend self\n    end",
    corrector: corrector
  )
end