""" Some hacks.

Written by Thomas Karolski (Thomas.Karolski@googlemail.com).

Last edit: 11.11.07

"""

def getframe(level=0):
	try:
		raise Exception() # make an error happen
	except: # and return the caller's frame
		import sys
		frame = sys.exc_traceback.tb_frame.f_back
		i = level
		while i < 0:
			if not hasattr(frame,'f_back') or frame.f_back == None:
				raise Exception("Can't get back "+str(level)+" levels")
			frame = frame.f_back
			i += 1
		
		return frame
				
import types
import weakref
from functools import wraps
class WeaklyReferencableMethod:
	def __init__(self, method):
		self._im_self = weakref.ref(method.im_self)
		self._im_class = method.im_class
		self._im_func = method.im_func 
		#update_wrapper(self._im_func, method)
		
	im_self = property(fget=lambda s: s._im_self())
	im_class = property(fget=lambda s: s._im_class)
	im_func = property(fget=lambda s: s._im_func)
		
	def __call__(self, *args, **dargs):
		return self.im_func(self.im_self, *args, **dargs)
	
import types
def weakrefhack( what ):
	"""weakrefhack( method )
	Checks whether method exists as an attribute inside
	method.im_self. If it does, a wrapper function is created
	which calls a WeaklyReferencableMethod class. The class
	only stores a weak reference to the original methods object
	instance (im_self). Thus we get 'real' weakly referencable
	methods.
	
	class A:
		def method( self ): pass
	a = A()
	referencable = weakrefhack(a.method)
	# referencable is a.method now
	ref = weakref.ref(a.method)"""
	what_type = type(what)
	
	if what_type==types.MethodType:
		for attrname in dir(what.im_self):
			if getattr(what.im_self, attrname)==what:
				wrm = WeaklyReferencableMethod(what)
				@wraps(what)
				def wrapper(*args, **dargs):
					wrm(*args, **dargs)
				wrapper.im_self = wrm.im_self
				wrapper.im_func = wrm.im_func
				wrapper.im_class = wrm.im_class
				setattr(what.im_self, attrname, wrapper)
				return wrapper

#import weakref
#class a:
#	def m():
#		pass
#
#mya = a()
#weakrefhack(mya.m)
#ref = weakref.ref(mya.m)
#print ref
#ref = weakref.ref(mya.m)
#print ref