class Ameba::Rule::Style::RedundantNext

Overview

A rule that disallows redundant next expressions. A next keyword allows a block to skip to the next iteration early, however, it is considered redundant in cases where it is the last expression in a block or combines into the node which is the last in a block.

For example, this is considered invalid:

block do |v|
  next v + 1
end
block do |v|
  case v
  when .nil?
    next "nil"
  when .blank?
    next "blank"
  else
    next "empty"
  end
end

And has to be written as the following:

block do |v|
  v + 1
end
block do |v|
  case arg
  when .nil?
    "nil"
  when .blank?
    "blank"
  else
    "empty"
  end
end

Configuration params

  1. allow_multi_next, default: true

Allows end-user to configure whether to report or not the next statements which yield tuple literals i.e.

block do
  next a, b
end

If this param equals to false, the block above will be forced to be written as:

block do
  {a, b}
end
  1. allow_empty_next, default: true

Allows end-user to configure whether to report or not the next statements without arguments. Sometimes such statements are used to yild the nil value explicitly.

block do
  @foo = :empty
  next
end

If this param equals to false, the block above will be forced to be written as:

block do
  @foo = :empty
  nil
end

YAML config example

Style/RedundantNext:
  Enabled: true
  AllowMultiNext: true
  AllowEmptyNext: true

Included Modules

Defined in:

ameba/rule/style/redundant_next.cr

Constant Summary

MSG = "Redundant `next` detected"

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from module Ameba::AST::Util

abort?(node) abort?, control_exp_code(node : Crystal::ControlExpression, code_lines) control_exp_code, dynamic_literal?(node) : Bool dynamic_literal?, exit?(node) exit?, flow_command?(node, in_loop) flow_command?, flow_expression?(node, in_loop = false) flow_expression?, literal?(node) : Bool literal?, loop?(node) loop?, name_end_location(node) name_end_location, name_location(node) name_location, name_size(node) name_size, node_source(node, code_lines) node_source, path_named?(node, name) : Bool path_named?, raise?(node) raise?, source_between(loc, end_loc, code_lines) : String | Nil source_between, static_literal?(node) : Bool static_literal?

Instance methods inherited from class Ameba::Rule::Base

==(other) ==, catch(source : Source) catch, excluded?(source) excluded?, group group, hash hash, name name, special? special?, test(source : Source, node : Crystal::ASTNode, *opts)
test(source : Source) test

Class methods inherited from class Ameba::Rule::Base

default_severity : Ameba::Severity default_severity

Macros inherited from class Ameba::Rule::Base

issue_for(*args, **kwargs, &block) issue_for

Macros inherited from module Ameba::Config::RuleConfig

properties(&block) properties

Constructor Detail

def self.new(ctx : YAML::ParseContext, node : YAML::Nodes::Node) #

def self.new(config = nil) #

A rule that disallows redundant next expressions. A next keyword allows a block to skip to the next iteration early, however, it is considered redundant in cases where it is the last expression in a block or combines into the node which is the last in a block.

For example, this is considered invalid:

block do |v|
  next v + 1
end
block do |v|
  case v
  when .nil?
    next "nil"
  when .blank?
    next "blank"
  else
    next "empty"
  end
end

And has to be written as the following:

block do |v|
  v + 1
end
block do |v|
  case arg
  when .nil?
    "nil"
  when .blank?
    "blank"
  else
    "empty"
  end
end

Configuration params

  1. allow_multi_next, default: true

Allows end-user to configure whether to report or not the next statements which yield tuple literals i.e.

block do
  next a, b
end

If this param equals to false, the block above will be forced to be written as:

block do
  {a, b}
end
  1. allow_empty_next, default: true

Allows end-user to configure whether to report or not the next statements without arguments. Sometimes such statements are used to yild the nil value explicitly.

block do
  @foo = :empty
  next
end

If this param equals to false, the block above will be forced to be written as:

block do
  @foo = :empty
  nil
end

YAML config example

Style/RedundantNext:
  Enabled: true
  AllowMultiNext: true
  AllowEmptyNext: true

[View source]

Class Method Detail

def self.parsed_doc : String | Nil #

Returns documentation for this rule, if there is any.

module Ameba
  # This is a test rule.
  # Does nothing.
  class MyRule < Ameba::Rule::Base
    def test(source)
    end
  end
end

MyRule.parsed_doc # => "This is a test rule.\nDoes nothing."

Instance Method Detail

def allow_empty_next=(allow_empty_next : Bool) #

def allow_empty_next? : Bool #

def allow_multi_next=(allow_multi_next : Bool) #

def allow_multi_next? : Bool #

def description : String #

def description=(description : String) #

def enabled=(enabled : Bool) #

def enabled? : Bool #

def excluded : Array(String) | Nil #

def excluded=(excluded : Array(String) | Nil) #

def severity : Ameba::Severity #

def severity=(severity : Ameba::Severity) #

def test(source, node : Crystal::Next, visitor : AST::RedundantControlExpressionVisitor) #

[View source]
def test(source, node : Crystal::Block) #

[View source]