fga-gpp-mds/2017.1-Escola-X

This cop checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric

This cop checks if the length of a method exceeds some maximum value. Comment lines can optionally be ignored. The maximum allowed length is configurable.

Too Many Instance Variables is a special case of LargeClass.

Example

Given this configuration

TooManyInstanceVariables:
  max_instance_variables: 3

and this code:

class TooManyInstanceVariables
  def initialize
    @arg_1 = :dummy
    @arg_2 = :dummy
    @arg_3 = :dummy
    @arg_4 = :dummy
  end
end

Reek would emit the following warning:

test.rb -- 5 warnings:
  [1]:TooManyInstanceVariables has at least 4 instance variables (TooManyInstanceVariables)

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.)

Classes should not assume that instance variables are set or present outside of the current class definition.

Good:

class Foo
  def initialize
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Good as well:

class Foo
  def foo?
    bar == :foo
  end
 
  def bar
    @bar ||= :foo
  end
end

Bad:

class Foo
  def go_foo!
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Example

Running Reek on:

class Dummy
  def test
    @ivar
  end
end

would report:

[1]:InstanceVariableAssumption: Dummy assumes too much for instance variable @ivar

Note that this example would trigger this smell warning as well:

class Parent
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    @omg
  end
end

The way to address the smell warning is that you should create an attr_reader to use @omg in the subclass and not access @omg directly like this:

class Parent
  attr_reader :omg
 
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    omg
  end
end

Directly accessing instance variables is considered a smell because it breaks encapsulation and makes it harder to reason about code.

If you don't want to expose those methods as public API just make them private like this:

class Parent
  def initialize(omg)
    @omg = omg
  end
 
  private
  attr_reader :omg
end
 
class Child < Parent
  def foo
    omg
  end
end

Current Support in Reek

An instance variable must:

• be set in the constructor
• or be accessed through a method with lazy initialization / memoization.

If not, Instance Variable Assumption will be reported.

Classes should not assume that instance variables are set or present outside of the current class definition.

Good:

class Foo
  def initialize
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Good as well:

class Foo
  def foo?
    bar == :foo
  end
 
  def bar
    @bar ||= :foo
  end
end

Bad:

class Foo
  def go_foo!
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Example

Running Reek on:

class Dummy
  def test
    @ivar
  end
end

would report:

[1]:InstanceVariableAssumption: Dummy assumes too much for instance variable @ivar

Note that this example would trigger this smell warning as well:

class Parent
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    @omg
  end
end

The way to address the smell warning is that you should create an attr_reader to use @omg in the subclass and not access @omg directly like this:

class Parent
  attr_reader :omg
 
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    omg
  end
end

Directly accessing instance variables is considered a smell because it breaks encapsulation and makes it harder to reason about code.

If you don't want to expose those methods as public API just make them private like this:

class Parent
  def initialize(omg)
    @omg = omg
  end
 
  private
  attr_reader :omg
end
 
class Child < Parent
  def foo
    omg
  end
end

Current Support in Reek

An instance variable must:

• be set in the constructor
• or be accessed through a method with lazy initialization / memoization.

If not, Instance Variable Assumption will be reported.

Classes should not assume that instance variables are set or present outside of the current class definition.

Good:

class Foo
  def initialize
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Good as well:

class Foo
  def foo?
    bar == :foo
  end
 
  def bar
    @bar ||= :foo
  end
end

Bad:

class Foo
  def go_foo!
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Example

Running Reek on:

class Dummy
  def test
    @ivar
  end
end

would report:

[1]:InstanceVariableAssumption: Dummy assumes too much for instance variable @ivar

Note that this example would trigger this smell warning as well:

class Parent
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    @omg
  end
end

The way to address the smell warning is that you should create an attr_reader to use @omg in the subclass and not access @omg directly like this:

class Parent
  attr_reader :omg
 
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    omg
  end
end

Directly accessing instance variables is considered a smell because it breaks encapsulation and makes it harder to reason about code.

If you don't want to expose those methods as public API just make them private like this:

class Parent
  def initialize(omg)
    @omg = omg
  end
 
  private
  attr_reader :omg
end
 
class Child < Parent
  def foo
    omg
  end
end

Current Support in Reek

An instance variable must:

• be set in the constructor
• or be accessed through a method with lazy initialization / memoization.

If not, Instance Variable Assumption will be reported.

Classes should not assume that instance variables are set or present outside of the current class definition.

Good:

class Foo
  def initialize
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Good as well:

class Foo
  def foo?
    bar == :foo
  end
 
  def bar
    @bar ||= :foo
  end
end

Bad:

class Foo
  def go_foo!
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Example

Running Reek on:

class Dummy
  def test
    @ivar
  end
end

would report:

[1]:InstanceVariableAssumption: Dummy assumes too much for instance variable @ivar

Note that this example would trigger this smell warning as well:

class Parent
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    @omg
  end
end

The way to address the smell warning is that you should create an attr_reader to use @omg in the subclass and not access @omg directly like this:

class Parent
  attr_reader :omg
 
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    omg
  end
end

Directly accessing instance variables is considered a smell because it breaks encapsulation and makes it harder to reason about code.

If you don't want to expose those methods as public API just make them private like this:

class Parent
  def initialize(omg)
    @omg = omg
  end
 
  private
  attr_reader :omg
end
 
class Child < Parent
  def foo
    omg
  end
end

Current Support in Reek

An instance variable must:

• be set in the constructor
• or be accessed through a method with lazy initialization / memoization.

If not, Instance Variable Assumption will be reported.

Classes should not assume that instance variables are set or present outside of the current class definition.

Good:

class Foo
  def initialize
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Good as well:

class Foo
  def foo?
    bar == :foo
  end
 
  def bar
    @bar ||= :foo
  end
end

Bad:

class Foo
  def go_foo!
    @bar = :foo
  end
 
  def foo?
    @bar == :foo
  end
end

Example

Running Reek on:

class Dummy
  def test
    @ivar
  end
end

would report:

[1]:InstanceVariableAssumption: Dummy assumes too much for instance variable @ivar

Note that this example would trigger this smell warning as well:

class Parent
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    @omg
  end
end

The way to address the smell warning is that you should create an attr_reader to use @omg in the subclass and not access @omg directly like this:

class Parent
  attr_reader :omg
 
  def initialize(omg)
    @omg = omg
  end
end
 
class Child < Parent
  def foo
    omg
  end
end

Directly accessing instance variables is considered a smell because it breaks encapsulation and makes it harder to reason about code.

If you don't want to expose those methods as public API just make them private like this:

class Parent
  def initialize(omg)
    @omg = omg
  end
 
  private
  attr_reader :omg
end
 
class Child < Parent
  def foo
    omg
  end
end

Current Support in Reek

An instance variable must:

• be set in the constructor
• or be accessed through a method with lazy initialization / memoization.

If not, Instance Variable Assumption will be reported.

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.

Check that the keys, separators, and values of a multi-line hash literal are aligned according to configuration. The configuration options are:

- key (left align keys)
- separator (align hash rockets and colons, right align keys)
- table (left align keys, hash rockets, and values)

The treatment of hashes passed as the last argument to a method call can also be configured. The options are:

- always_inspect
- always_ignore
- ignore_implicit (without curly braces)
- ignore_explicit (with curly braces)

Example:

# EnforcedHashRocketStyle: key (default)
# EnforcedColonStyle: key (default)
 
# good
{
  foo: bar,
  ba: baz
}
{
  :foo => bar,
  :ba => baz
}
 
# bad
{
  foo: bar,
   ba: baz
}
{
  :foo => bar,
   :ba => baz
}

Example:

# EnforcedHashRocketStyle: separator
# EnforcedColonStyle: separator
 
#good
{
  foo: bar,
   ba: baz
}
{
  :foo => bar,
   :ba => baz
}
 
#bad
{
  foo: bar,
  ba: baz
}
{
  :foo => bar,
  :ba => baz
}
{
  :foo => bar,
  :ba  => baz
}

Example:

# EnforcedHashRocketStyle: table
# EnforcedColonStyle: table
 
#good
{
  foo: bar,
  ba:  baz
}
{
  :foo => bar,
  :ba  => baz
}
 
#bad
{
  foo: bar,
  ba: baz
}
{
  :foo => bar,
   :ba => baz
}

Use a guard clause instead of wrapping the code inside a conditional expression

Example:

# bad
def test
  if something
    work
  end
end
 
# good
def test
  return unless something
  work
end
 
# also good
def test
  work if something
end
 
# bad
if something
  raise 'exception'
else
  ok
end
 
# good
raise 'exception' if something
ok

Checks for colon (:) not followed by some kind of space. N.B. this cop does not handle spaces after a ternary operator, which are instead handled by Layout/SpaceAroundOperators.

Example:

# bad
def f(a:, b:2); {a:3}; end
 
# good
def f(a:, b: 2); {a: 3}; end

Checks for comma (,) not followed by some kind of space.

Example:

# bad
[1,2]
{ foo:bar,}
 
# good
[1, 2]
{ foo:bar, }

Modifiers should be indented as deep as method definitions, or as deep as the class/module keyword, depending on configuration.

Example: EnforcedStyle: indent (default)

# bad
class Plumbus
private
  def smooth; end
end
 
# good
class Plumbus
  private
  def smooth; end
end

Example: EnforcedStyle: outdent

# bad
class Plumbus
  private
  def smooth; end
end
 
# good
class Plumbus
private
  def smooth; end
end

Checks for space between a method name and a left parenthesis in defs.

Example:

# bad
def func (x) end
def method= (y) end
 
# good
def func(x) end
def method=(y) end

Access modifiers should be surrounded by blank lines.

Example:

# bad
class Foo
  def bar; end
  private
  def baz; end
end
 
# good
class Foo
  def bar; end
 
  private
 
  def baz; end
end

Checks for colon (:) not followed by some kind of space. N.B. this cop does not handle spaces after a ternary operator, which are instead handled by Layout/SpaceAroundOperators.

Example:

# bad
def f(a:, b:2); {a:3}; end
 
# good
def f(a:, b: 2); {a: 3}; end

Checks for colon (:) not followed by some kind of space. N.B. this cop does not handle spaces after a ternary operator, which are instead handled by Layout/SpaceAroundOperators.

Example:

# bad
def f(a:, b:2); {a:3}; end
 
# good
def f(a:, b: 2); {a: 3}; end

Checks for space between a method name and a left parenthesis in defs.

Example:

# bad
def func (x) end
def method= (y) end
 
# good
def func(x) end
def method=(y) end

This cop checks for the presence of superfluous parentheses around the condition of if/unless/while/until.

Example:

# bad
x += 1 while (x < 10)
foo unless (bar || baz)
 
if (x > 10)
elsif (x < 3)
end
 
# good
x += 1 while x < 10
foo unless bar || baz
 
if x > 10
elsif x < 3
end

This cop checks for redundant parentheses.

Example:

# bad
(x) if ((y.z).nil?)
 
# good
x if y.z.nil?

This cop checks for uses of and and or, and suggests using && and || instead. It can be configured to check only in conditions, or in all contexts.

Example: EnforcedStyle: always (default)

# bad
foo.save and return
 
# bad
if foo and bar
end
 
# good
foo.save && return
 
# good
if foo && bar
end

Example: EnforcedStyle: conditionals

# bad
if foo and bar
end
 
# good
foo.save && return
 
# good
foo.save and return
 
# good
if foo && bar
end

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"
 
# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'
 
# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks for colon (:) not followed by some kind of space. N.B. this cop does not handle spaces after a ternary operator, which are instead handled by Layout/SpaceAroundOperators.

Example:

# bad
def f(a:, b:2); {a:3}; end
 
# good
def f(a:, b: 2); {a: 3}; end

Checks for uses of if with a negated condition. Only ifs without else are considered. There are three different styles:

- both
- prefix
- postfix

Example: EnforcedStyle: both (default)

# enforces `unless` for `prefix` and `postfix` conditionals
 
# bad
 
if !foo
  bar
end
 
# good
 
unless foo
  bar
end
 
# bad
 
bar if !foo
 
# good
 
bar unless foo

Example: EnforcedStyle: prefix

# enforces `unless` for just `prefix` conditionals
 
# bad
 
if !foo
  bar
end
 
# good
 
unless foo
  bar
end
 
# good
 
bar if !foo

Example: EnforcedStyle: postfix

# enforces `unless` for just `postfix` conditionals
 
# bad
 
bar if !foo
 
# good
 
bar unless foo
 
# good
 
if !foo
  bar
end

Checks for uses of if with a negated condition. Only ifs without else are considered. There are three different styles:

- both
- prefix
- postfix

Example: EnforcedStyle: both (default)

# enforces `unless` for `prefix` and `postfix` conditionals
 
# bad
 
if !foo
  bar
end
 
# good
 
unless foo
  bar
end
 
# bad
 
bar if !foo
 
# good
 
bar unless foo

Example: EnforcedStyle: prefix

# enforces `unless` for just `prefix` conditionals
 
# bad
 
if !foo
  bar
end
 
# good
 
unless foo
  bar
end
 
# good
 
bar if !foo

Example: EnforcedStyle: postfix

# enforces `unless` for just `postfix` conditionals
 
# bad
 
bar if !foo
 
# good
 
bar unless foo
 
# good
 
if !foo
  bar
end

Use next to skip iteration instead of a condition at the end.

Example: EnforcedStyle: skipmodifierifs (default)

# bad
[1, 2].each do |a|
  if a == 1
    puts a
  end
end
 
# good
[1, 2].each do |a|
  next unless a == 1
  puts a
end
 
# good
[1, 2].each do |o|
  puts o unless o == 1
end

Example: EnforcedStyle: always

# With `always` all conditions at the end of an iteration needs to be
# replaced by next - with `skip_modifier_ifs` the modifier if like
# this one are ignored: `[1, 2].each { |a| return 'yes' if a == 1 }`
 
# bad
[1, 2].each do |o|
  puts o unless o == 1
end
 
# bad
[1, 2].each do |a|
  if a == 1
    puts a
  end
end
 
# good
[1, 2].each do |a|
  next unless a == 1
  puts a
end

Use a guard clause instead of wrapping the code inside a conditional expression

Example:

# bad
def test
  if something
    work
  end
end
 
# good
def test
  return unless something
  work
end
 
# also good
def test
  work if something
end
 
# bad
if something
  raise 'exception'
else
  ok
end
 
# good
raise 'exception' if something
ok