rikai/Showbot

A method with Too Many Statements is any method that has a large number of lines.

Too Many Statements warns about any method that has more than 5 statements. Reek's smell detector for Too Many Statements counts +1 for every simple statement in a method and +1 for every statement within a control structure (if, else, case, when, for, while, until, begin, rescue) but it doesn't count the control structure itself.

So the following method would score +6 in Reek's statement-counting algorithm:

def parse(arg, argv, &error)
  if !(val = arg) and (argv.empty? or /\A-/ =~ (val = argv[0]))
    return nil, block, nil                                         # +1
  end
  opt = (val = parse_arg(val, &error))[1]                          # +2
  val = conv_arg(*val)                                             # +3
  if opt and !arg
    argv.shift                                                     # +4
  else
    val[0] = nil                                                   # +5
  end
  val                                                              # +6
end

(You might argue that the two assigments within the first @if@ should count as statements, and that perhaps the nested assignment should count as +2.)

Repeated Conditional is a special case of Simulated Polymorphism. Basically it means you are checking the same value throughout a single class and take decisions based on this.

Example

Given

class RepeatedConditionals
  attr_accessor :switch

  def repeat_1
    puts "Repeat 1!" if switch
  end

  def repeat_2
    puts "Repeat 2!" if switch
  end

  def repeat_3
    puts "Repeat 3!" if switch
  end
end

Reek would emit the following warning:

test.rb -- 4 warnings:
  [5, 9, 13]:RepeatedConditionals tests switch at least 3 times (RepeatedConditional)

If you get this warning then you are probably not using the right abstraction or even more probable, missing an additional abstraction.

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

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.

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.

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

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

A NilCheck is a type check. Failures of NilCheck violate the "tell, don't ask" principle.

Additionally, type checks often mask bigger problems in your source code like not using OOP and / or polymorphism when you should.

Example

Given

class Klass
  def nil_checker(argument)
    if argument.nil?
      puts "argument isn't nil!"
    end
  end
end

Reek would emit the following warning:

test.rb -- 1 warning:
  [3]:Klass#nil_checker performs a nil-check. (NilCheck)

A NilCheck is a type check. Failures of NilCheck violate the "tell, don't ask" principle.

Additionally, type checks often mask bigger problems in your source code like not using OOP and / or polymorphism when you should.

Example

Given

class Klass
  def nil_checker(argument)
    if argument.nil?
      puts "argument isn't nil!"
    end
  end
end

Reek would emit the following warning:

test.rb -- 1 warning:
  [3]:Klass#nil_checker performs a nil-check. (NilCheck)

A NilCheck is a type check. Failures of NilCheck violate the "tell, don't ask" principle.

Additionally, type checks often mask bigger problems in your source code like not using OOP and / or polymorphism when you should.

Example

Given

class Klass
  def nil_checker(argument)
    if argument.nil?
      puts "argument isn't nil!"
    end
  end
end

Reek would emit the following warning:

test.rb -- 1 warning:
  [3]:Klass#nil_checker performs a nil-check. (NilCheck)

A NilCheck is a type check. Failures of NilCheck violate the "tell, don't ask" principle.

Additionally, type checks often mask bigger problems in your source code like not using OOP and / or polymorphism when you should.

Example

Given

class Klass
  def nil_checker(argument)
    if argument.nil?
      puts "argument isn't nil!"
    end
  end
end

Reek would emit the following warning:

test.rb -- 1 warning:
  [3]:Klass#nil_checker performs a nil-check. (NilCheck)

A NilCheck is a type check. Failures of NilCheck violate the "tell, don't ask" principle.

Additionally, type checks often mask bigger problems in your source code like not using OOP and / or polymorphism when you should.

Example

Given

class Klass
  def nil_checker(argument)
    if argument.nil?
      puts "argument isn't nil!"
    end
  end
end

Reek would emit the following warning:

test.rb -- 1 warning:
  [3]:Klass#nil_checker performs a nil-check. (NilCheck)

A Utility Function is any instance method that has no dependency on the state of the instance.

Unused Parameter refers to methods with parameters that are unused in scope of the method.

Having unused parameters in a method is code smell because leaving dead code in a method can never improve the method and it makes the code confusing to read.

Example

Given:

class Klass
  def unused_parameters(x,y,z)
    puts x,y # but not z
  end
end

Reek would emit the following warning:

[2]:Klass#unused_parameters has unused parameter 'z' (UnusedParameters)

Unused Parameter refers to methods with parameters that are unused in scope of the method.

Having unused parameters in a method is code smell because leaving dead code in a method can never improve the method and it makes the code confusing to read.

Example

Given:

class Klass
  def unused_parameters(x,y,z)
    puts x,y # but not z
  end
end

Reek would emit the following warning:

[2]:Klass#unused_parameters has unused parameter 'z' (UnusedParameters)

Unused Parameter refers to methods with parameters that are unused in scope of the method.

Having unused parameters in a method is code smell because leaving dead code in a method can never improve the method and it makes the code confusing to read.

Example

Given:

class Klass
  def unused_parameters(x,y,z)
    puts x,y # but not z
  end
end

Reek would emit the following warning:

[2]:Klass#unused_parameters has unused parameter 'z' (UnusedParameters)

This cop checks for unused method arguments.

Example:

# bad

def some_method(used, unused, _unused_but_allowed)
  puts used
end

Example:

# good

def some_method(used, _unused, _unused_but_allowed)
  puts used
end

This cop checks for unused method arguments.

Example:

# bad

def some_method(used, unused, _unused_but_allowed)
  puts used
end

Example:

# good

def some_method(used, _unused, _unused_but_allowed)
  puts used
end

This cop checks for redundant access modifiers, including those with no code, those which are repeated, and leading public modifiers in a class or module body. Conditionally-defined methods are considered as always being defined, and thus access modifiers guarding such methods are not redundant.

Example:

class Foo
  public # this is redundant (default access is public)

  def method
  end

  private # this is not redundant (a method is defined)
  def method2
  end

  private # this is redundant (no following methods are defined)
end

Example:

class Foo
  # The following is not redundant (conditionally defined methods are
  # considered as always defining a method)
  private

  if condition?
    def method
    end
  end

  protected # this is not redundant (method is defined)

  define_method(:method2) do
  end

  protected # this is redundant (repeated from previous modifier)

  [1,2,3].each do |i|
    define_method("foo#{i}") do
    end
  end

  # The following is redundant (methods defined on the class'
  # singleton class are not affected by the public modifier)
  public

  def self.method3
  end
end

Example:

# Lint/UselessAccessModifier:
#   ContextCreatingMethods:
#     - concerning
require 'active_support/concern'
class Foo
  concerning :Bar do
    def some_public_method
    end

    private

    def some_private_method
    end
  end

  # this is not redundant because `concerning` created its own context
  private

  def some_other_private_method
  end
end

Example:

# Lint/UselessAccessModifier:
#   MethodCreatingMethods:
#     - delegate
require 'active_support/core_ext/module/delegation'
class Foo
  # this is not redundant because `delegate` creates methods
  private

  delegate :method_a, to: :method_b
end