RubyCodingConvention

(DRAFT VERSION: 2001/11/01)

File Names

Directory and File names and Suffixes

Ruby source codefile/directory name is lower case class/module name with suffix '.rb'.

ex.Foo class => foo.rbBar module => bar.rbFooBar class => foobar.rb (Normal Rule)

foo_bar.rb (Rails Rule)Foo::Bar class => foo/bar.rb

Libraries*1

non-standard multiple files required by a script should be in one directory, and they shouldbe 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 whichscript 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:

* 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 barself

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 forDocumentation Comments, and '#' for both Documentation Comments and ImplementationComments.

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 == 2true # special case

elseprime?(a) # work only for odd a

end

Documentation Comments

Header/Footer

=begin

= FooBar library

== What's New?.........

== Installation.........

....

=end

In Class/Module

# .....# ....#def foo()

..

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 mayconfuse readers of your script.

Definitions

Initialization

Ruby variables have no 'definitions'. So, you should initialize variables.

One initialization per line

level = 0size = 0

is preferred over

level = size = 0

Placement

Statements

Simple Statements

Each line should contain at most one statement.

foo = 1 ## Correctbar = 2 ## Correct

foo = 1; bar = 2 ## AVOID!

Compound Statements

if-end, if-else-end, if-elsif-else-end Statements

simple example:

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 foowhen condition1

<statements>when condition2

<statements>else

<statements>end

begin-rescue-end Statements

It handles errors (Exceptions).

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 ## Correcta + b ## Correcta+ b ## AVOID!a +b ## AVOID! (Erroneous: interpreted as a(+b))

a += b + ca = (a + b) / (c * d)a = bfoo("foo" + buz + bar)

Naming Conventions

Classes/Modules

class and module names should be nouns; in mixed case with the first letter of each internalword capitalized.

ex: class Raster, class Raster::ImageSprite

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 = 1some_char = SomeChar.new()table_width = 0.0

Constants

constants should be all upper case with words separated by underscores ('_'). *2

ex:MIN_LENGTH = 1DEFAULT_HOST = "foo.example.com"

Omission

Speaking of 'Connection Pool' as a variable, you should decide to prefer name by scope suchas 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

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::ClassBx = cb::method_c( a )y = cb::method_d( b )

You can also do:

include ModuleAx = ClassB::method_c(a)y = ClassB::method_d(b)

Code Example

Ruby Source File Example

=beginblahdy/blah.rb$Id:$

Copyright (c) 2001 TAKAHASHI Masayoshi

This is free software; you can copy and distribute and modifythis 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#

module Blahdy

class Blah < SomeClass# A class implementation comment goes here.

# CLASS_VAR1 documentation commentCLASS_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

*1any arguments?

*2Huh, is there a reasonable background to distinguish constants from a class name which is a constant at the

same time?