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Ruby_Coding_Convention

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Ruby_Coding_Convention

  1. 1. RubyCodingConvention (DRAFT VERSION: 2001/11/01) File Names Directory and File names and Suffixes Ruby source code file/directory name is lower case class/module name with suffix '.rb'. ex. Foo class => foo.rb Bar module => bar.rb FooBar class => foobar.rb (Normal Rule) foo_bar.rb (Rails Rule) Foo::Bar class => foo/bar.rb *1 Libraries non-standard multiple files required by a script should be in one directory, and they should be installed to the standard site-ruby directory or a script's library directory. don't use a current directory for libraries --- it is dangerous. since the directory in which script exists can not be specified portably, it is also not suited for libraries. File Organization • require (if necessary) • include (if necessary) • classes and modules definition • main • testing code(?) using __FILE__ idiom ex: if __FILE__ == $0 <testcode> end Beginning Comment begin - end style for file header or footer. =begin * Name: * Description * Author: * Date:
  2. 2. * License: =end using '#' style for class/module and method definitions # using foo bar # # foo bar buz. # class Foo # bar.bar.bar. # class Bar # constructor of Bar. # def initialize(bar = nil) super(bar) end def bar self end end def initialize() end end Indentation Line length Max length is about 80 characters. Wrapping Line • Break after comma • Break after operator Comments Ruby has two comments style: =begin...=end and '#'. You should use =begin...=end for Documentation Comments, and '#' for both Documentation Comments and Implementation Comments.
  3. 3. Implementation Comments Block Comments # Here is block comment. # # foo, bar, buz. Single-Line Comments # this is single line comment. ## this is also single line comment. Tailing Comments if a == 2 true # special case else prime?(a) # work only for odd a end Documentation Comments Header/Footer =begin = FooBar library == What's New? ..... .... == Installation ..... .... .... =end In Class/Module # ..... # .... # def foo() ..
  4. 4. or ## # ..... # .... # def foo() .. Way of no commenting If you can write simple, short and light scripts, comments may not be necessary. You can let the script itself tell everything, instead of embedding documentation that may confuse readers of your script. Definitions Initialization Ruby variables have no 'definitions'. So, you should initialize variables. One initialization per line level = 0 size = 0 is preferred over level = size = 0 Placement Statements Simple Statements Each line should contain at most one statement. foo = 1 ## Correct bar = 2 ## Correct foo = 1; bar = 2 ## AVOID! Compound Statements if-end, if-else-end, if-elsif-else-end Statements simple example:
  5. 5. if <condition> <statements> end more complex example: if <condition> <statements> elsif <condition> <statements> else <statements> end You can put on <condition> after <statements> when <statements> is one-line. <statements> if <condition> block methods `{...}' style: bar.foo(vars){|vars2| <statements> } `do...end' style: bar.foo(vars) do |vars2| <statements> end one-line block: bar.foo(){|var| <statements> } case-when Statements Ruby's case-when (not when-case) does not need 'break'. case foo when condition1 <statements> when condition2 <statements> else <statements> end begin-rescue-end Statements It handles errors (Exceptions).
  6. 6. begin <statements> rescue FooError => e <statements> rescue BazError => e2 <statements> rescue <statements> end White Space Blank Lines • Between sections of a source file • Between class and module definitions • Between methods • Before blocks or single-line comments • Between logical sections inside a method to improve readability Blank spaces A keyword followed by a parenthesis should be separated by a space. ex: while (foo.end?) { <statements> } The number of spaces should be balanced. a+b ## Correct a + b ## Correct a+ b ## AVOID! a +b ## AVOID! (Erroneous: interpreted as a(+b)) a += b + c a = (a + b) / (c * d) a = b foo(quot;fooquot; + buz + bar) Naming Conventions Classes/Modules class and module names should be nouns; in mixed case with the first letter of each internal word capitalized. ex: class Raster, class Raster::ImageSprite
  7. 7. Methods Methods should be verbs. All lower case ASCII letters with words separated by underscores ('_') ex. run(), run_fast(), obj.background_color() Variables variable names should be all lower case ASCII letters with words separated by underscore ('_') ex: i = 1 some_char = SomeChar.new() table_width = 0.0 Constants *2 constants should be all upper case with words separated by underscores ('_'). ex: MIN_LENGTH = 1 DEFAULT_HOST = quot;foo.example.comquot; Omission Speaking of 'Connection Pool' as a variable, you should decide to prefer name by scope such as the following... • 'conpool' for local scope (such as local variable) • '@connection_pool' for class scope (such as instance variable) Pragmatic Programming Practices Using attr_* to access def foo() @foo end attr_reader :foo Without Parenthesis Some methods are used without parenthesis. • require ex. require 'foo/bar' • include
  8. 8. ex. include FooModule • p ex. p foo • attr_* ex. attr_reader :foo, :bar Reduce repetition When successive lines of a script share something, x = ModuleA::ClassB::method_c( a ) y = ModuleA::ClassB::method_d( b ) (-- 'function' => 'method' --) you should make it like this: cb = ModuleA::ClassB x = cb::method_c( a ) y = cb::method_d( b ) You can also do: include ModuleA x = ClassB::method_c(a) y = ClassB::method_d(b) Code Example Ruby Source File Example =begin blahdy/blah.rb $Id:$ Copyright (c) 2001 TAKAHASHI Masayoshi This is free software; you can copy and distribute and modify this program under the term of Ruby's License (http://www.ruby-lang.org/LINCENSE.txt) =end # # module description goes here. # # @version: 1.82 # @author: TAKAHASHI Masayoshi #
  9. 9. module Blahdy class Blah < SomeClass # A class implementation comment goes here. # CLASS_VAR1 documentation comment CLASS_VAR1 = 1; # CLASS_VAR2 documentation comment that happens # to be more than one line length. # CLASS_VAR2 = 1; # ...constructor Blah documentation comment... # def initialize() ## ...implementation goes here... end # ...method do_something documentation comment... # def do_sometiong() ## ...implementation goes here... end # ...method do_something_else documentation comment... # # @param some_param description # def do_something_else(some_param) ## ...implementation goes here... end end end *1 any arguments? *2 Huh, is there a reasonable background to distinguish constants from a class name which is a constant at the same time?

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