UsersController assumes too much for instance variable '@user' Open
class UsersController < 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.
UsersController has no descriptive comment Open
class UsersController < 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
Keep a blank line before and after private
. Open
private
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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
Inconsistent indentation detected. Open
def set_user
@user = User.find(params[:id])
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 UsersController < 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
Use %i
or %I
for an array of symbols. Open
before_action :set_user, only: [:show, :update, :destroy]
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This cop can check for array literals made up of symbols that are not using the %i() syntax.
Alternatively, it checks for symbol arrays using the %i() syntax on projects which do not want to use that syntax.
Configuration option: MinSize
If set, arrays with fewer elements than this value will not trigger the
cop. For example, a MinSize of
3` will not enforce a style on an array
of 2 or fewer elements.
Example: EnforcedStyle: percent (default)
# good
%i[foo bar baz]
# bad
[:foo, :bar, :baz]
Example: EnforcedStyle: brackets
# good
[:foo, :bar, :baz]
# bad
%i[foo bar baz]
Inconsistent indentation detected. Open
def user_params
params.require(:user).permit(:full_name, :email_address)
end
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This cops checks for inconsistent indentation.
Example:
class A
def test
puts 'hello'
puts 'world'
end
end
Line is too long. [88/80] Open
# Never trust parameters from the scary internet, only allow the white list through.
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Use %i
or %I
for an array of symbols. Open
before_action :snakeize_params, only: [:create, :update]
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- Exclude checks
This cop can check for array literals made up of symbols that are not using the %i() syntax.
Alternatively, it checks for symbol arrays using the %i() syntax on projects which do not want to use that syntax.
Configuration option: MinSize
If set, arrays with fewer elements than this value will not trigger the
cop. For example, a MinSize of
3` will not enforce a style on an array
of 2 or fewer elements.
Example: EnforcedStyle: percent (default)
# good
%i[foo bar baz]
# bad
[:foo, :bar, :baz]
Example: EnforcedStyle: brackets
# good
[:foo, :bar, :baz]
# bad
%i[foo bar baz]
Put empty method definitions on a single line. Open
def show
end
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This cop checks for the formatting of empty method definitions.
By default it enforces empty method definitions to go on a single
line (compact style), but it can be configured to enforce the end
to go on its own line (expanded style).
Note: A method definition is not considered empty if it contains comments.
Example: EnforcedStyle: compact (default)
# bad
def foo(bar)
end
def self.foo(bar)
end
# good
def foo(bar); end
def foo(bar)
# baz
end
def self.foo(bar); end
Example: EnforcedStyle: expanded
# bad
def foo(bar); end
def self.foo(bar); end
# good
def foo(bar)
end
def self.foo(bar)
end