def installmethod(function, object, name = None):
"""
This function adds either a bound method to an instance or
an unbound method to a class. If name is ommited it defaults
to the name of the given function.
Example:
a = A()
def f(self, x, y):
self.z = x + y
installmethod(f, A, "add")
a.add(2, 4)
print a.z
installmethod(lambda self, i: self.l[i], a, "listIndex")
print a.listIndex(5)
"""
from types import ClassType, MethodType, InstanceType
if name == None:
name = function.func_name
else:
function = renamefunction(function, name)
if type(object) == ClassType:
setattr(object, name,
MethodType(function, None, object))
elif type(object) == InstanceType:
setattr(object, name,
MethodType(function, object, object.__class__))
else:
raise TypeError
def renamefunction(function, name):
"""
This function returns a function identical to the given one, but
with the given name.
"""
from types import FunctionType, CodeType
c = function.func_code
if c.co_name != name:
# rename the code object.
c = CodeType(c.co_argcount, c.co_nlocals, c.co_stacksize,
c.co_flags, c.co_code, c.co_consts,
c.co_names, c.co_varnames, c.co_filename,
name, c.co_firstlineno, c.co_lnotab)
if function.func_defaults != None:
return FunctionType(c, function.func_globals, name,
function.func_defaults)
return FunctionType(c, function.func_globals, name)
if __name__ == '__main__':
# example
class Widget:
def installButton(self, name):
def f(self, name=name):
print name, 'pressed'
installmethod(f, self, name)
a = Widget()
a.installButton('foo')
a.foo()
# AttributeError: Widget().foo()
def f(self, x, y):
self.z = x + y
Widget.add = renamefunction(f, "add")
a.add(2, 4)
print a.z
installmethod(lambda self, i: self.l[i], Widget, "listIndex")
a.l = list("abc")
print a.listIndex(1)
# TypeError: a.add(2, 4, 6)
