From: 7stud -- <bbxx789_05ss@...>
Date: 2011-08-25T06:28:40+09:00
Subject: Re: New to Ruby some problems

Jeff Moore wrote in post #1018257:
> jack jones wrote in post #1018220:
>> Thank you very much Chuck Remes :)
>> The problem is I don't understand those functions :
>> # now name just [] = ?? The problem is that I don't get the magic
>>     10    def []=(row, column, value) # how does it works?
>>     11      position = index row, column
>>     12      @array[position] = value
>>     13    end
>>     15    # retrieve value from row, column
>>     16    def [](row, column)
>>     17      position = index row, column
>>     18      return @array[position]
>>     19    end
>
> '[]=' is actually a method. Does that help?

More precisely, '[]=' is the name of the method.  You can name a method 
with three letters, right?

def abc(str)
  puts str
end

This is the same:

def []=(str)
  puts str
end


The name of the first method is 'abc', and the name of the second method 
is '[]='.  Here is an example:


class Dog
  def abc(str)
    puts str
  end

  def []=(str)
    puts str
  end
end


d = Dog.new
d.abc('hello')
d.[]=('world')

--output:--
hello
world


So in ruby, the []= method is just a method with a funny looking name 
that is hard to pronounce.  However, in the case of []= ruby lets you do 
some special things; you can call []= like this:

d[val1] = val2

and ruby translates that into:

d.[]=(val1, val2)


Here is a more complete example:

class Dog
  attr_reader :attributes

  def initialize
    @attributes = {}
  end

  def abc(str)
    puts str
  end

  def []=(key, val)
    @attributes[key] = val
  end
end


d = Dog.new
d.abc('hello')
d['greeting'] = 'world'

p d.attributes


--output:--
hello
{"greeting"=>"world"}









 However, ruby does some tricky things with the second method, so you 
can call it like this:

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