beanieboi/ffprober

A module is usually a mixin, so when an #initialize method is present it is hard to tell initialization order and parameters so having #initialize in a module is usually a bad idea.

Example

The Foo module below contains a method initialize. Although class B inherits from A, the inclusion of Foo stops A#initialize from being called.

class A
  def initialize(a)
    @a = a
  end
end

module Foo
  def initialize(foo)
    @foo = foo
  end
end

class B < A
  include Foo

  def initialize(b)
    super('bar')
    @b = b
  end
end

A simple solution is to rename Foo#initialize and call that method by name:

module Foo
  def setup_foo_module(foo)
    @foo = foo
  end
end

class B < A
  include Foo

  def initialize(b)
    super 'bar'
    setup_foo_module('foo')
    @b = b
  end
end

Classes and modules are the units of reuse and release. It is therefore considered good practice to annotate every class and module with a brief comment outlining its responsibilities.

Example

Given

class Dummy
  # Do things...
end

Reek would emit the following warning:

test.rb -- 1 warning:
  [1]:Dummy has no descriptive comment (IrresponsibleModule)

Fixing this is simple - just an explaining comment:

# The Dummy class is responsible for ...
class Dummy
  # Do things...
end

Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.

Reek implements a check for Duplicate Method Call.

Example

Here's a very much simplified and contrived example. The following method will report a warning:

def double_thing()
  @other.thing + @other.thing
end

One quick approach to silence Reek would be to refactor the code thus:

def double_thing()
  thing = @other.thing
  thing + thing
end

A slightly different approach would be to replace all calls of double_thing by calls to @other.double_thing:

class Other
  def double_thing()
    thing + thing
  end
end

The approach you take will depend on balancing other factors in your code.