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View class_and_module_methods.rb
def modules_including_module(target_module)
ObjectSpace.each_object(Module).select do |object|
# All Class'es are modules, but we are not interested in them, so we exclude them.
!object.is_a?(Class) \
&& \
object.ancestors.include?(target_module) \
&& \
View modules_needing_included_method.rb
# Any module (not class) that includes SemanticLogger::Loggable must also implement an
# `included` method that gets the including class to also include SemanticLogger::Loggable.
# This is because the module's instance method `logger`, when it becomes part of the including
# class, will look for `self.class.logger` when called, and `self` will evaluate to the instance
# of the class and not the module. Having the class include `Loggable` will cause a class method
# `logger` to be created so that this will work.
# This method returns the modules that have included Loggable but do not have an `included`
# method implementation. This is an imperfect test since we are not testing the content of that
# implementation, but I don't know a better way.
keithrbennett / module-method-doesnt-override-class-instance-method.rb
Last active September 18, 2022 07:54
Shows that a module instance method will not overwrite a class instance method of the same name if `include` is used, but *will* if `prepend` is used.
View module-method-doesnt-override-class-instance-method.rb
#!/usr/bin/env ruby
module M
def foo
puts 'I am a module instance method.'
# Class whose foo instance method is defined *after* the include.
class C1
keithrbennett / force_class_inclusion_of_module.rb
Last active September 15, 2022 15:01
Illustrates forcing inclusion of a module by another included module in Ruby.
View force_class_inclusion_of_module.rb
#!/usr/bin/env ruby
# From solution at
module M1
def m1; puts 'M1 was included by M2.'; end
module M2
def self.included(including_class)
View semantic_logger_trap.rb
#!/usr/bin/env ruby
# Illustrates cycling through the SemanticLogger log levels with signals.
# For reference by
require 'semantic_logger'
# Redefine add_signal_handler to output to STDERR (omit TTIN behavior for brevity):
module SemanticLogger
def self.add_signal_handler(log_level_signal = "USR2", thread_dump_signal = "TTIN", gc_log_microseconds = 100_000)
keithrbennett / trap_user_signals.rb
Created July 28, 2022 04:56
Illustrates the use of 'trap' in Ruby for crude interprocess communication
View trap_user_signals.rb
#!/usr/bin/env ruby
# Author: @keithrbennett (Github)
# Illustrates how to respond to Unix signals in a Ruby program, using SIGUSR1 and SIGUSR2
# for user-defined signals, and SIGINT for trapping Ctrl-C.
require 'awesome_print'
require 'json'
require 'yaml'
View xml.rb
#!/usr/bin/env ruby
require 'nokogiri'
def process_example(message, xml_text, use_noblanks_option)
puts message
puts "XML text: #{xml_text.inspect}"
doc = Nokogiri::XML(xml_text) { |config| use_noblanks_option ? config.noblanks : config }
puts 'Resulting XML document:'
puts doc.inspect; puts; puts
keithrbennett / rfg-set-up-repos.rb
Last active September 23, 2021 00:50
Installs all repos needed for Ruby for Good 2021.
View rfg-set-up-repos.rb
#!/usr/bin/env ruby
keithrbennett / module-class-state.rb
Last active April 13, 2021 20:17
Illustrates that Ruby modules *can* have state but only on the module level, not the instance level.
View module-class-state.rb
#!/usr/bin/env ruby
module M
class << self
attr_accessor :foo
class C1
def call
keithrbennett / gist:18f10124354d62eb8ba5feafaa9b39dc
Last active February 15, 2021 20:13
Simple Ractor test based on Koichi's example at
View gist:18f10124354d62eb8ba5feafaa9b39dc
#!/usr/bin/env ruby
# Run in directory containing `compar.c`, e.g. from
require 'etc'
WORDS = Ractor.make_shareable File.readlines('/usr/share/dict/words').map(&:chomp).map(&:downcase).sort
TRY_COUNT = Etc.nprocessors
puts "Measuring first sequentially on main ractor and then with #{TRY_COUNT} ractors:\n\n"