HomeController has at least 5 instance variables Open
class HomeController < ApplicationController
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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)
HomeController has no descriptive comment Open
class HomeController < ApplicationController
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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
HomeController assumes too much for instance variable '@user' Open
class HomeController < ApplicationController
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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.
Inconsistent indentation detected. Open
def user
return unless current_user
@user = User.find(current_user.id)
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Inconsistent indentation detected. Open
def store_user_groups
@user_groups = @user.groups.order(updated_at: :desc)
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Inconsistent indentation detected. Open
def resource
@resource ||= User.new
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Inconsistent indentation detected. Open
def store_user_events
user_events = @user.events_from_groups
@events_count = user_events.size
@events = EventDecorator.collection(user_events.limit(6))
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Missing top-level class documentation comment. Open
class HomeController < ApplicationController
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This cop checks for missing top-level documentation of classes and modules. Classes with no body are exempt from the check and so are namespace modules - modules that have nothing in their bodies except classes, other modules, or constant definitions.
The documentation requirement is annulled if the class or module has a "#:nodoc:" comment next to it. Likewise, "#:nodoc: all" does the same for all its children.
Example:
# bad
class Person
# ...
end
# good
# Description/Explanation of Person class
class Person
# ...
end
Inconsistent indentation detected. Open
helper_method :resource, :resource_name
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Inconsistent indentation detected. Open
def limit
current_user ? 3 : 6
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Inconsistent indentation detected. Open
def resource_name
:user
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Inconsistent indentation detected. Open
def store_unhidden_groups
@unhidden_groups = Group.unhidden.random_selection(limit)
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end