Class extending

just playing around with ruby ( experimenting ). hopefully someone can help :p anyways... everytime I do this code

Quote:

---

class MYLIB
def s
self.to_s
end

def i
self.to_i
end

def f
self.to_f
end
end

class String < MYLIB

end

class Integer < MYLIB

end

---

I keep getting this error

Quote:

---

classes.rb:15: superclass mismatch for class String (TypeError)

---

line 15 being this code

Quote:

---

class String < MYLIB

---

String (and Integer) already has a superclass, and I don't think you can change that dynamically at runtime.

Why would you do this anyway? It seems like poor application design, or that you are trying to use a feature (class extensions) just for the sake of using it.

like I said... I'm just playing around... experimenting

If you want to experiment with class extensions you could try something like this:

PHP Code:

---

class Array
    def puts_each
        self.each do |item|
            puts item.to_s
        end
    end    
end

["one","two","three"].puts_each 


---

Remember that you are only extending an existing class, you cannot change it (make it a subclass of something else, for example).

thx's I've been doing that kinda of stuff already

just that when I got this code

Quote:

---

def s
self.to_s
end

def i
self.to_i
end

def f
self.to_f
end

---

inside 3 seperate classes ( String, Integer, Float ) ... kinda makes the code abit bloated... so I thought I just do a class which has them in and add them on to the other classes considering all 3 classes gonna be doing the same when calling to them

There is a better way of doing that - modules and mixins.

Code:

---

module LazyConversions
  def s
    self.to_s
  end

  def i
    self.to_i
  end

  def f
    self.to_f
  end
end

class String
  include LazyConversions
end

class Integer
  include LazyConversions
end

1.s    #=>  "1"

---

ah thx's... didn't know about the "include" part... thats what I basically needed