From: Jeff Swope <jeff.swope@...>
Date: 2007-12-04T12:58:58+09:00
Subject: Re: Class method

------=_Part_12414_27855323.1196740740380
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

why does line 2 state initialize instead of breed?

Here's the modified example - p050newdog.rb

  1. class NewDog
  2.   def initialize(breed)
  3.     @breed = breed
  4.   end
  5.   attr_reader :breed, :name # create reader only
  6.
  7.   # setter method
  8.   def name=(nm)
  9.     @name = nm
 10.   end
 11. end
 12.
 13. nd = NewDog.new('Doberman')
 14. #nd.name=('Benzy')
 15. nd.name = 'Benzy'
 16. puts nd.name



On Dec 3, 2007 8:33 PM, Nathan Viswa <nathanv@rogers.com> wrote:

> Found this in
> http://rubylearning.com/satishtalim/ruby_syntactic_sugar.html
> Describes
> def methodname=     usage
>
> Programmers use the term syntactic sugar to refer to special rules that
> let you write your code in a way that doesn't correspond to the normal
> rules but that is easier to remember how to do and looks better.
>
> Let us say we want to set the name of a dog. As a starting point, name
> can be set along with everything else at object creation time, as in the
> example below.
>
>   1. class NewDog
>   2.   def initialize(breed, name)
>   3.     @breed = breed
>   4.     @name = name
>   5.   end
>   6.   attr_reader :breed, :name   # create reader only
>   7. end
>   8. nd = NewDog.new('Doberman', 'Benzy')
>   9. puts nd.name
>
> class NewDog def initialize(breed, name) @breed = breed @name = name end
> attr_reader :breed, :name # create reader only end nd =
> NewDog.new('Doberman', 'Benzy') puts nd.name
>
> Let's write a set_name method that allows us to set, or reset, the name
> of an existing dog. We'll also rewrite the initialize method so that it
> doesn't expect a name:
>
>   1. class NewDog
>   2.   def initialize(breed)
>   3.     @breed = breed
>   4.   end
>   5.   attr_reader :breed, :name   # create reader only
>   6.   # setter method
>   7.   def set_name(nm)
>   8.     @name = nm
>   9.   end
>  10. end
>  11. nd = NewDog.new('Doberman')
>  12. nd.set_name('Benzy')
>  13. puts nd.name
>
> class NewDog def initialize(breed) @breed = breed end attr_reader
> :breed, :name # create reader only # setter method def set_name(nm)
> @name = nm end end nd = NewDog.new('Doberman') nd.set_name('Benzy') puts
> nd.name
>
> Ruby allows you to define methods that end with an equal sign (=). Let's
> replace set_name with a method called name=
>
>   1. def name=(nm)
>   2.   @name = nm
>   3. end
>
> def name=(nm) @name = nm end
>
> name= does exactly what set_name did, and in spite of the slightly odd
> method name, you can call it just like any other method:
>
>   1. nd.name=('Benzy')
>
> nd.name=('Benzy')
>
> Here's the modified example - p050newdog.rb
>
>   1. class NewDog
>   2.   def initialize(breed)
>   3.     @breed = breed
>   4.   end
>   5.   attr_reader :breed, :name # create reader only
>   6.
>   7.   # setter method
>   8.   def name=(nm)
>   9.     @name = nm
>  10.   end
>  11. end
>  12.
>  13. nd = NewDog.new('Doberman')
>  14. #nd.name=('Benzy')
>  15. nd.name = 'Benzy'
>  16. puts nd.name
>
> class NewDog def initialize(breed) @breed = breed end attr_reader
> :breed, :name # create reader only # setter method def name=(nm) @name =
> nm end end nd = NewDog.new('Doberman') #nd.name=('Benzy') nd.name =
> 'Benzy' puts nd.name
>
> The equal sign gives you that familiar "assigning a value to something"
> feeling, so you know you're dealing with a setter method. It still looks
> odd, but Ruby takes care of that, too.
>
> Ruby gives you some syntactic sugar for calling setter methods. Instead
> of this:
>
>   1. nd.name=('Benzy')
>
> nd.name=('Benzy')
>
> you're allowed to do this:
>
>   1. nd.name = 'Benzy'
>
> nd.name = 'Benzy'
>
> When the interpreter sees the message "name" followed by " =", it
> automatically ignores the space before equal sign and reads the single
> message "name=" - a call to the method whose name is name=, which we've
> defined. As for the right-hand side: parentheses are optional on single
> arguments to methods, so you can just put 'Benzy' there and it will be
> picked up as the argument to the name= method.
>
> IN RAILS: Method calls using the equal-sign syntax are common in Rails
> applications.
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

------=_Part_12414_27855323.1196740740380--