From: 7stud -- <bbxx789_05ss@...>
Date: 2007-11-13T14:22:45+09:00
Subject: Re: name of a variable, at runtime

Colin Summers wrote:
> Well, technically it will be a Rails object, so I don't create it,
> ActiveRecord does, but I bet the send(part) thing will work. Thanks.
> This will make a really LOOOOONG table get generated with a few lines
> of code instead.
> 
> --Colin

In case you wanted an explanation of how things work, take a look at 
this example:


class Human
  def knee=(str)
    @knee = str
  end

  def knee
    return @knee
  end

end

fred = Human.new
fred.knee = 'plastic'
puts fred.knee
--->plastic


When you write:

fred.knee = 'plastic'

you are actually calling a method--the method named 'knee='.  In Ruby, 
method names can have characters like  '=' and '?' in them.   When the 
method 'knee=' is called, the statement in the body of the method is 
executed, and that statement assigns a value to the member variable 
@knee.

Likewise, when you write:

puts fred.knee

that calls the method named 'knee', and the knee method is defined to 
return the value of the member variable @knee.

Therefore, the problem you were faced with becomes: how do you call a 
method if you have the name of the method as a string.  That's where 
Object#send comes in--it allows you to do just that.

Although it wouldn't make much sense, you could actually define the 
knee= method like this:

class Human
  def knee=(str)
    @head = str
  end

  def head
    return @head
  end

end

fred = Human.new
fred.knee = 'steel'
puts fred.head
--->steel


-- 
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