Ruby

The doc for Mutex_m should remind the user of the necessity of calling super() in each class that includes Mutex_m.

The average user will do:

require 'mutex_m' class A include Mutex_m def initialize myval @myval = myval # error: no super() end def method @myval end end a = A.new 'abc' a.mu_synchronize{a.method} 

He will get:

NoMethodError: undefined method `synchronize' for nil:NilClass	from /usr/lib64/ruby/2.4.0/mutex_m.rb:74:in `mu_synchronize' 

and will lose the rest of the evening trying to understand what went wrong ;-)