xlarsx · March 4, 2011 20:01 · Mar 4, 2011
diff --git a/UsoPythonWith.py b/UsoPythonWith.py
@@ -0,0 +1,52 @@
+class Canvas(object):
+    def __init__(self, lock):
+        self.lock = lock
+
+    def __enter__(self):
+        ContenedorCanvas.estableceObjeto(self)
+        return self
+
+    def __exit__(self, type, value, tb):
+        ContenedorCanvas.terminaUsarObjeto(self)
+
+    def obtenTexto(self):
+        return self.lock
+
+
+class Scatter(object):
+    def __init__(self, num):
+        self.canvas = Canvas("Canvas: " + str(num))
+
+
+class ContenedorCanvas(object):
+    pilaObjetos = []
+
+    @staticmethod
+    def estableceObjeto(objeto):
+        if objeto not in ContenedorCanvas.pilaObjetos:
+            ContenedorCanvas.pilaObjetos.append(objeto)
+
+    @staticmethod
+    def terminaUsarObjeto(objeto):
+        if objeto in ContenedorCanvas.pilaObjetos:
+            ContenedorCanvas.pilaObjetos.remove(objeto)
+
+    @staticmethod
+    def obtenUltimoElemento():
+        return ContenedorCanvas.pilaObjetos[-1] if len(ContenedorCanvas.pilaObjetos) > 0 else None
+
+
+class Rectangle(object):
+    def __init__(self):
+        ultimoElemento = ContenedorCanvas.obtenUltimoElemento()
+        if ultimoElemento is not None:
+            print "Dibujando rectangulo en %s" % ultimoElemento.obtenTexto()
+
+
+node = Scatter(1)
+node2 = Scatter(2)
+
+with node.canvas:
+    Rectangle() # Solicitud de dibujar rectangulo en Canvas 1
+    with node2.canvas:
+        Rectangle() # Solicitud de dibujar rectangulo en Canvas 2