Exception: Com::AbstractMethodError

Inherits:
StandardError
  • Object
show all
Includes:
StandardError
Defined in:
lib/com/abstract_method_error.rb

Overview

Represents errors related to “abstract” methods.

Despite Ruby does not have conception of abstract methods usually developers do want to force concrete classes to provide implementation for the method called from base class. In that case called method with assumed obligatory implementation in concrete classes can be desided as abstract method.

Class Method Summary collapse

Class Method Details

.method_not_overridden_error(klass, method_name) ⇒ ::Com::AbstractMethodError

Examples:


# @abstract
class Base
  def call
    # here might be some other calls

    # call to abstract method
    very_important_job
  end

  # @abstract
  #
  # @raise ::Com::AbstractMethodError when actual implementation has not
  #   been provided in concrete class
  def very_important_job
    raise ::Com::AbstractMethodError.method_not_overridden_error(self.class, __method__)
  end
end

class Concrete < Base
  def useful_method
    # imagine here some implementation of useful work
  end
end

# finally we use Concrete class
concreate_instance = Concrete.new

# Here we get an exception that very_important_job method suppose to be
# overridden in Concrete class.
concreate_instance.call

# Exact exception will look like
# Com::AbstractMethodError: Method 'very_important_job' has to be overridden in 'Concrete' class.
#          from (irb):14:in `very_important_job'
#          from (irb):6:in `call'
#          from (irb):29
#          from bin/console:14:in `<main>'

Parameters:

  • klass (Class) —

    class instance in which method had to override default implementaion

  • method_name (String) —

    name of the method which have to be overridden

Returns:



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# File 'lib/com/abstract_method_error.rb', line 59

def self.method_not_overridden_error(klass, method_name)
  self.new("Method '#{method_name}' has to be overridden in '#{klass}' class.")
end