Ruby基础语法使用方法全套讲解，风格讲解指南大全

# Ruby Style Guide This is Airbnb's Ruby Style Guide. It was inspired by [GitHub's guide](https://web.archive.org/web/20160410033955/https://github.com/styleguide/ruby) and [RuboCop's guide][rubocop-guide]. Airbnb also maintains a [JavaScript Style Guide][airbnb-javascript]. ## Table of Contents 1. [Whitespace](#whitespace) 1. [Indentation](#indentation) 1. [Inline](#inline) 1. [Newlines](#newlines) 1. [Line Length](#line-length) 1. [Commenting](#commenting) 1. [File/class-level comments](#fileclass-level-comments) 1. [Function comments](#function-comments) 1. [Block and inline comments](#block-and-inline-comments) 1. [Punctuation, spelling, and grammar](#punctuation-spelling-and-grammar) 1. [TODO comments](#todo-comments) 1. [Commented-out code](#commented-out-code) 1. [Methods](#methods) 1. [Method definitions](#method-definitions) 1. [Method calls](#method-calls) 1. [Conditional Expressions](#conditional-expressions) 1. [Conditional keywords](#conditional-keywords) 1. [Ternary operator](#ternary-operator) 1. [Syntax](#syntax) 1. [Naming](#naming) 1. [Classes](#classes) 1. [Exceptions](#exceptions) 1. [Collections](#collections) 1. [Strings](#strings) 1. [Regular Expressions](#regular-expressions) 1. [Percent Literals](#percent-literals) 1. [Rails](#rails) 1. [Scopes](#scopes) 1. [Be Consistent](#be-consistent) 1. [Translation](#translation) ## Whitespace ### Indentation * <a name="default-indentation"></a>Use soft-tabs with a two-space indent.^{[[link](#default-indentation)]} * <a name="indent-when-as-case"></a>Indent `when` as deep as `case`. ^{[[link](#indent-when-as-case)]} ```ruby case when song.name == 'Misty' puts 'Not again!' when song.duration > 120 puts 'Too long!' when Time.now.hour > 21 puts "It's too late" else song.play end kind = case year when 1850..1889 then 'Blues' when 1890..1909 then 'Ragtime' when 1910..1929 then 'New Orleans Jazz' when 1930..1939 then 'Swing' when 1940..1950 then 'Bebop' else 'Jazz' end ``` * <a name="align-function-params"></a>Align function parameters either all on the same line or one per line.^{[[link](#align-function-params)]} ```ruby # bad def self.create_translation(phrase_id, phrase_key, target_locale, value, user_id, do_xss_check, allow_verification) ... end # good def self.create_translation(phrase_id, phrase_key, target_locale, value, user_id, do_xss_check, allow_verification) ... end # good def self.create_translation( phrase_id, phrase_key, target_locale, value, user_id, do_xss_check, allow_verification ) ... end ``` * <a name="indent-multi-line-bool"></a>Indent succeeding lines in multi-line boolean expressions.^{[[link](#indent-multi-line-bool)]} ```ruby # bad def is_eligible?(user) Trebuchet.current.launch?(ProgramEligibilityHelper::PROGRAM_TREBUCHET_FLAG) && is_in_program?(user) && program_not_expired end # good def is_eligible?(user) Trebuchet.current.launch?(ProgramEligibilityHelper::PROGRAM_TREBUCHET_FLAG) && is_in_program?(user) && program_not_expired end ``` ### Inline * <a name="trailing-whitespace"></a>Never leave trailing whitespace. ^{[[link](#trailing-whitespace)]} * <a name="space-before-comments"></a>When making inline comments, include a space between the end of the code and the start of your comment. ^{[[link](#space-before-comments)]} ```ruby # bad result = func(a, b)# we might want to change b to c # good result = func(a, b) # we might want to change b to c ``` * <a name="spaces-operators"></a>Use spaces around operators; after commas, colons, and semicolons; and around `{` and before `}`. ^{[[link](#spaces-operators)]} ```ruby sum = 1 + 2 a, b = 1, 2 1 > 2 ? true : false; puts 'Hi' [1, 2, 3].each { |e| puts e } ``` * <a name="no-space-before-commas"></a>Never include a space before a comma. ^{[[link](#no-space-before-commas)]} ```ruby result = func(a, b) ``` * <a name="spaces-block-params"></a>Do not include space inside block parameter pipes. Include one space between parameters in a block. Include one space outside block parameter pipes. ^{[[link](#spaces-block-params)]} ```ruby # bad {}.each { | x, y |puts x } # good {}.each { |x, y| puts x } ``` * <a name="no-space-after-!"></a>Do not leave space between `!` and its argument.^{[[link](#no-space-after-!)]} ```ruby !something ``` * <a name="no-spaces-braces"></a>No spaces after `(`, `[` or before `]`, `)`. ^{[[link](#no-spaces-braces)]} ```ruby some(arg).other [1, 2, 3].length ``` * <a name="no-spaces-string-interpolation"></a>Omit whitespace when doing string interpolation.^{[[link](#no-spaces-string-interpolation)]} ```ruby # bad var = "This #{ foobar } is interpolated." # good var = "This #{foobar} is interpolated." ``` * <a name="no-spaces-range-literals"></a>Don't use extra whitespace in range literals.^{[[link](#no-spaces-range-literals)]} ```ruby # bad (0 ... coll).each do |item| # good (0...coll).each do |item| ``` ### Newlines * <a name="multiline-if-newline"></a>Add a new line after `if` conditions spanning multiple lines to help differentiate between the conditions and the body. ^{[[link](#multiline-if-newline)]} ```ruby if @reservation_alteration.checkin == @reservation.start_date && @reservation_alteration.checkout == (@reservation.start_date + @reservation.nights) redirect_to_alteration @reservation_alteration end ``` * <a name="newline-after-conditional"></a>Add a new line after conditionals, blocks, case statements, etc.^{[[link](#newline-after-conditional)]} ```ruby if robot.is_awesome? send_robot_present end robot.add_trait(:human_like_intelligence) ``` * <a name="newline-different-indent"></a>Don’t include newlines between areas of different indentation (such as around class or module bodies). ^{[[link](#newline-different-indent)]} ```ruby # bad class Foo def bar # body omitted end end # good class Foo def bar # body omitted end end ``` * <a name="newline-between-methods"></a>Include one, but no more than one, new line between methods.^{[[link](#newline-between-methods)]} ```ruby def a end def b end ``` * <a name="method-def-empty-lines"></a>Use a single empty line to break between statements to break up methods into logical paragraphs internally. ^{[[link](#method-def-empty-lines)]} ```ruby def transformorize_car car = manufacture(options) t = transformer(robot, disguise) car.after_market_mod! t.transform(car) car.assign_cool_name! fleet.add(car) car end ``` * <a name="trailing-newline"></a>End each file with a newline. Don't include multiple newlines at the end of a file. ^{[[link](#trailing-newline)]} ## Line Length * Keep each line of code to a readable length. Unless you have a reason not to, keep lines to fewer than 100 characters. ([rationale](./rationales.md#line-length