A bizarre problem with data= methods

ruby-talk
1

Hi all.

I have found an error that does not understand. Look this simple code:

···

---------------------------------
class Foo
  def value=(data)
    puts "Look #{data}"
  end
end

f = Foo.new.value = "at me" # => Look at me
---------------------------------

Great! A little assigner that works perfectly. But now I make a
constructor that use the assigner directly:

---------------------------------
class Foo
  def initialize(data)
    value = data
  end

  def value=(data)
    puts "Look #{data}"
  end
end

f = Foo.new("at me") # => Nothing!!!!!!!!!
---------------------------------

Why? The constructor doesn't use value= method. What is happening? Is
that normal?

Thanl you for your help.

--
DaVinci

2

You need an explicit self, ie. `self.value = data`. Without the `self`, Ruby
interprets that line as a local variable assignment, not a method call.

···

2009/8/27 David Espada <davinciSINSPAM@escomposlinuxagujero-negro.org>

Hi all.

I have found an error that does not understand. Look this simple code:

---------------------------------
class Foo
def value=(data)
   puts "Look #{data}"
end
end

f = Foo.new.value = "at me" # => Look at me
---------------------------------

Great! A little assigner that works perfectly. But now I make a
constructor that use the assigner directly:

---------------------------------
class Foo
def initialize(data)
   value = data
end

def value=(data)
   puts "Look #{data}"
end
end

f = Foo.new("at me") # => Nothing!!!!!!!!!
---------------------------------

Why? The constructor doesn't use value= method. What is happening? Is
that normal?

--
James Coglan
http://jcoglan.com

3

It has sense. Other form, Ruby might search all methods of class in each
local assignment.

Thank you.

···

El jueves 27 de agosto, James Coglan escribió:

You need an explicit self, ie. `self.value = data`. Without the
`self`, Ruby interprets that line as a local variable assignment, not
a method call.

--
DaVinci