BLSQ/orbf2

This cop checks for memoized methods whose instance variable name does not match the method name.

This cop can be configured with the EnforcedStyleForLeadingUnderscores directive. It can be configured to allow for memoized instance variables prefixed with an underscore. Prefixing ivars with an underscore is a convention that is used to implicitly indicate that an ivar should not be set or referencd outside of the memoization method.

Example: EnforcedStyleForLeadingUnderscores: disallowed (default)

# bad
# Method foo is memoized using an instance variable that is
# not `@foo`. This can cause confusion and bugs.
def foo
  @something ||= calculate_expensive_thing
end

# good
def _foo
  @foo ||= calculate_expensive_thing
end

# good
def foo
  @foo ||= calculate_expensive_thing
end

# good
def foo
  @foo ||= begin
    calculate_expensive_thing
  end
end

# good
def foo
  helper_variable = something_we_need_to_calculate_foo
  @foo ||= calculate_expensive_thing(helper_variable)
end

Example: EnforcedStyleForLeadingUnderscores: required

# bad
def foo
  @something ||= calculate_expensive_thing
end

# bad
def foo
  @foo ||= calculate_expensive_thing
end

# good
def foo
  @_foo ||= calculate_expensive_thing
end

# good
def _foo
  @_foo ||= calculate_expensive_thing
end

Example: EnforcedStyleForLeadingUnderscores :optional

# bad
def foo
  @something ||= calculate_expensive_thing
end

# good
def foo
  @foo ||= calculate_expensive_thing
end

# good
def foo
  @_foo ||= calculate_expensive_thing
end

# good
def _foo
  @_foo ||= calculate_expensive_thing
end

This cop is designed to help upgrade to after Ruby 3.0. It will add the comment # frozen_string_literal: true to the top of files to enable frozen string literals. Frozen string literals may be default after Ruby 3.0. The comment will be added below a shebang and encoding comment. The frozen string literal comment is only valid in Ruby 2.3+.

Example: EnforcedStyle: always (default)

# The `always` style will always add the frozen string literal comment
# to a file, regardless of the Ruby version or if `freeze` or `<<` are
# called on a string literal.
# bad
module Bar
  # ...
end

# good
# frozen_string_literal: true

module Bar
  # ...
end

Example: EnforcedStyle: never

# The `never` will enforce that the frozen string literal comment does
# not exist in a file.
# bad
# frozen_string_literal: true

module Baz
  # ...
end

# good
module Baz
  # ...
end

This cop checks for duplicated instance (or singleton) method definitions.

Example:

# bad

def foo
  1
end

def foo
  2
end

Example:

# bad

def foo
  1
end

alias foo bar

Example:

# good

def foo
  1
end

def bar
  2
end

Example:

# good

def foo
  1
end

alias bar foo