How would you design a very “Pythonic” UI framework?

Question

I have been playing with the Ruby library \"shoes\". Basically you can write a GUI application in the following way:

Shoes.app do
  t = para \"Not clicked!\"
  b         


        

Answer 1

This is extremely contrived and not pythonic at all, but here's my attempt at a semi-literal translation using the new "with" statement.

with Shoes():
  t = Para("Not clicked!")
  with Button("The Label"):
    Alert("You clicked the button!")
    t.replace("Clicked!")

The hardest part is dealing with the fact that python will not give us anonymous functions with more than one statement in them. To get around that, we could create a list of commands and run through those...

Anyway, here's the backend code I ran this with:

context = None

class Nestable(object):
  def __init__(self,caption=None):
    self.caption = caption
    self.things = []

    global context
    if context:
      context.add(self)

  def __enter__(self):
    global context
    self.parent = context
    context = self

  def __exit__(self, type, value, traceback):
    global context
    context = self.parent

  def add(self,thing):
    self.things.append(thing)
    print "Adding a %s to %s" % (thing,self)

  def __str__(self):
    return "%s(%s)" % (self.__class__.__name__, self.caption)


class Shoes(Nestable):
  pass

class Button(Nestable):
  pass

class Alert(Nestable):
  pass

class Para(Nestable):
  def replace(self,caption):
    Command(self,"replace",caption)

class Command(Nestable):
  def __init__(self, target, command, caption):
    self.command = command
    self.target  = target
    Nestable.__init__(self,caption)

  def __str__(self):
    return "Command(%s text of %s with \"%s\")" % (self.command, self.target, self.caption)

  def execute(self):
    self.target.caption = self.caption