danini-the-panini/mittsu

This cop checks for underscore-prefixed variables that are actually used.

Example:

# bad

[1, 2, 3].each do |_num|
  do_something(_num)
end

Example:

# good

[1, 2, 3].each do |num|
  do_something(num)
end

Example:

# good

[1, 2, 3].each do |_num|
  do_something # not using `_num`
end

This cop checks for underscore-prefixed variables that are actually used.

Example:

# bad

[1, 2, 3].each do |_num|
  do_something(_num)
end

Example:

# good

[1, 2, 3].each do |num|
  do_something(num)
end

Example:

# good

[1, 2, 3].each do |_num|
  do_something # not using `_num`
end

This cop checks for unused block arguments.

Example:

# bad

do_something do |used, unused|
  puts used
end

do_something do |bar|
  puts :foo
end

define_method(:foo) do |bar|
  puts :baz
end

Example:

#good

do_something do |used, _unused|
  puts used
end

do_something do
  puts :foo
end

define_method(:foo) do |_bar|
  puts :baz
end

This cop checks for underscore-prefixed variables that are actually used.

Example:

# bad

[1, 2, 3].each do |_num|
  do_something(_num)
end

Example:

# good

[1, 2, 3].each do |num|
  do_something(num)
end

Example:

# good

[1, 2, 3].each do |_num|
  do_something # not using `_num`
end

This cop checks for underscore-prefixed variables that are actually used.

Example:

# bad

[1, 2, 3].each do |_num|
  do_something(_num)
end

Example:

# good

[1, 2, 3].each do |num|
  do_something(num)
end

Example:

# good

[1, 2, 3].each do |_num|
  do_something # not using `_num`
end

This cop checks for every useless assignment to local variable in every scope. The basic idea for this cop was from the warning of ruby -cw:

assigned but unused variable - foo

Currently this cop has advanced logic that detects unreferenced reassignments and properly handles varied cases such as branch, loop, rescue, ensure, etc.

Example:

# bad

def some_method
  some_var = 1
  do_something
end

Example:

# good

def some_method
  some_var = 1
  do_something(some_var)
end

This cop checks for assignments in the conditions of if/while/until.

Example:

# bad

if some_var = true
  do_something
end

Example:

# good

if some_var == true
  do_something
end