Self modifying systems question
Erik Max Francis
max at alcyone.com
Wed Apr 30 10:11:58 CEST 2003
Sten Kvamme wrote:
> Self modifying code is a well known technology. Has anyone done this
> Python? What I'm seeking for is examples of software that adds to
> itself (methods and variables) in runtime. I'd like an instantiated
> object to
> be able to add a method to itself.
Oh yeah, Python can do this just fine. Dynamic attribute addition is
actually the normal way things are done; after all, that's all that an
__init__ method does (provided the class doesn't have __slots__) -- it
adds attributes. It's customary, for maintainability's sake, to add
everything all at once, but there's no reason you can't add more later.
Same thing with "methods" -- all you really need is an attribute that's
callable. If you want something that has access to the self instance,
you can just pass that along as well.
>>> class C: pass
>>> c = C()
<__main__.C instance at 0x8159244>
>>> c.x = 1
>>> c.f = lambda t: t**2
>>> c.xSquared = lambda self=c: self.x**2
>>> c.x = 10
Erik Max Francis / max at alcyone.com / http://www.alcyone.com/max/
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