Subclassing built-in classes

MonkeeSage MonkeeSage at
Thu Oct 5 13:49:57 CEST 2006

I know that python doesn't allow extending built-in objects like the
str class; but you can subclass them using a class of the same name and
thus shadow them to get the same general effect (albeit you have to use
the explicit constructor rather than literals).

class str(str):
  def display(self):
    print self

I was just playing around and realized that assigning to
__builtins__.str (or if you prefer sys.modules['__builtin__'].str) has
the same effect.

class mystr(str):
  def display(self):
    print self
__builtins__.str = mystr

So that made me wonder...couldn't python (in theory) allow for literals
to use extended classes by using the object in __builtins__.<class> as
the class for literals? By default it would be the standard base class,
but it could also be a custom subclass. Would that be possible / easy /
worthwhile to do?


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