3scale/porta

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.)

In general, a Data Clump occurs when the same two or three items frequently appear together in classes and parameter lists, or when a group of instance variable names start or end with similar substrings.

The recurrence of the items often means there is duplicate code spread around to handle them. There may be an abstraction missing from the code, making the system harder to understand.

Example

Given

class Dummy
  def x(y1,y2); end
  def y(y1,y2); end
  def z(y1,y2); end
end

Reek would emit the following warning:

test.rb -- 1 warning:
  [2, 3, 4]:Dummy takes parameters [y1, y2] to 3 methods (DataClump)

A possible way to fix this problem (quoting from Martin Fowler):

The first step is to replace data clumps with objects and use the objects whenever you see them. An immediate benefit is that you'll shrink some parameter lists. The interesting stuff happens as you begin to look for behavior to move into the new objects.

A class that publishes a setter for an instance variable invites client classes to become too intimate with its inner workings, and in particular with its representation of state.

The same holds to a lesser extent for getters, but Reek doesn't flag those.

Example

Given:

class Klass
  attr_accessor :dummy
end

Reek would emit the following warning:

reek test.rb

test.rb -- 1 warning:
  [2]:Klass declares the writable attribute dummy (Attribute)

A candidate method for the Missing Safe Method smell are methods whose names end with an exclamation mark.

An exclamation mark in method names means (the explanation below is taken from here ):

The ! in method names that end with ! means, “This method is dangerous”—or, more precisely, this method is the “dangerous” version of an otherwise equivalent method, with the same name minus the !. “Danger” is relative; the ! doesn’t mean anything at all unless the method name it’s in corresponds to a similar but bang-less method name. So, for example, gsub! is the dangerous version of gsub. exit! is the dangerous version of exit. flatten! is the dangerous version of flatten. And so forth.

Such a method is called Missing Safe Method if and only if her non-bang version does not exist and this method is reported as a smell.

Example

Given

class C
  def foo; end
  def foo!; end
  def bar!; end
end

Reek would report bar! as Missing Safe Method smell but not foo!.

Reek reports this smell only in a class context, not in a module context in order to allow perfectly legit code like this:

class Parent
  def foo; end
end

module Dangerous
  def foo!; end
end

class Son < Parent
  include Dangerous
end

class Daughter < Parent
end

In this example, Reek would not report the Missing Safe Method smell for the method foo of the Dangerous module.