Class: WhyClasses::Rules::FunctionBucket

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

Overview

Rule 2 (summary): "If it's named after a design pattern, it's probably a workaround for a less flexible language." The classic service object -- a class with a single call/perform/run instance method and no state -- is a bucket for a function.

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/function_bucket.rb', line 12

def self.description
  "Class with a single call/perform/run method and no state -> use a module function."
end

Instance Method Details

#on_class(node) ⇒ Object 



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

def on_class(node)
  s = shape(node)
  return if s.name.nil?
  return if configuration.framework_base_class?(s.superclass)
  return if s.superclass? # framework/base subclasses handled above; other inheritance is separate
  return unless function_bucket?(s)

  method = s.behavior_methods.first.children[0]
  add_offense(
    node,
    message: "#{s.name} is a bucket for a single function (`##{method}`) with no state.",
    suggestion: "Prefer a module function or a plain method:\n" \
                "    module #{s.name}\n      module_function\n\n" \
                "      def #{method}(...)\n        ...\n      end\n    end\n" \
                "  Callers become `#{s.name}.#{method}(...)` with no throwaway instance."
  )
end