From: Doug H <doug00@...>
Date: 2005-12-21T08:42:49+09:00
Subject: Re: Bruce Eckel wouldn't know why to switch from Python to Ruby


gabriele renzi wrote:
> rcoder ha scritto:
> > Eckel's article is getting pretty long in the tooth at this point -- I
> > remember reading it back when I was a Python user several years ago,
> > and it actually delayed my swith to Ruby for a few months, at least. I
> > probably don't qualify as a Python expert, but after being exposed to
> > both for non-trivial projects, there are definitely some differences
> > that make me prefer Ruby.
> >
> > First, because all object "slots" in Python are public, (stupid
> > conventions like underscore prefixes aside) you see a lot of code like
> > this:
> >
> > obj.setFoo("bar")
> >
> > This is because 'obj.foo = "bar"' is a direct assignment, with no
> > method call involved.
>
> I think you'have been away from python far too long, recent python (3 or
> 4 versions I think_) has a nice thing called properties.
> Basically you can declare "foo" to have setters and getters when you
> need it, and still threat them in the same way (i.e. "obj.foo = bar"
> becomes a method call). 80% of the times someone writing a setFoo or
> getFoo is doing it because (s)he was a java/c++ developer.

Properties in python don't work with subclasses, however.

#python:

class A(object):
	def __init__(self):
		self.x = 0
	def getX(self):
		return self.x
	def setX(self, val):
		self.x = val
	X = property(fget=getX, fset=setX)

class B(A):
	def getX(self):
		return self.x + 1

b = B()
print b.X   # 0 instead of 1, uh oh

#######################

#ruby:

class A
	attr_accessor :X
	def initialize
		@X = 0
	end
end
class B<A
	def X
		@X+1
	end
end

b = B.new
puts b.X  # 1