|
|
|
# $Id: __init__.py,v 1.2 2011-08-31 18:26:18 wirawan Exp $
|
|
|
|
#
|
|
|
|
# wpylib.py module
|
|
|
|
# Created: 20110608
|
|
|
|
# Wirawan Purwanto
|
|
|
|
#
|
|
|
|
# Module space for advanced tools requiring low-level python hacks.
|
|
|
|
#
|
|
|
|
|
|
|
|
import sys
|
|
|
|
import new
|
|
|
|
|
|
|
|
"""
|
|
|
|
wpylib.py module
|
|
|
|
Collection of low-level pythonic hacks
|
|
|
|
|
|
|
|
Instance method hacks
|
|
|
|
---------------------
|
|
|
|
|
|
|
|
make_unbound_instance_method::
|
|
|
|
make_unbound_method::
|
|
|
|
|
|
|
|
One possible reason of using these routines is to provide an
|
|
|
|
alterable calling point with different implementations--somewhat like
|
|
|
|
virtual methods, but something that can be changed dynamically
|
|
|
|
on-the-fly.
|
|
|
|
NOTE: The trick provided by wpylib.py.im_ref.im_ref class is
|
|
|
|
a better way to accomplish the same thing.
|
|
|
|
|
|
|
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
def make_unbound_instance_method(method):
|
|
|
|
"""Generates an unbound instance method from a possibly bound
|
|
|
|
instance method.
|
|
|
|
"""
|
|
|
|
return new.instancemethod(method.im_func, None, method.im_class)
|
|
|
|
|
|
|
|
|
|
|
|
def make_unbound_method(method):
|
|
|
|
"""Generates an unbound instance method from a possibly bound
|
|
|
|
instance method, or even user-defined function.
|
|
|
|
This is useful for injecting external, completely unrelated function
|
|
|
|
as an instance procedure into a class, without having to subclass
|
|
|
|
the whole thing.
|
|
|
|
CAVEAT: This is a haram trick. Know what you are doing."""
|
|
|
|
try:
|
|
|
|
return new.instancemethod(method.im_func, None, method.im_class)
|
|
|
|
except AttributeError:
|
|
|
|
# Assume this is a static method or user-defined external method
|
|
|
|
# injected into this class.
|
|
|
|
return method
|
|
|
|
|
|
|
|
|
|
|
|
def make_weakly_bound_method(method, instance):
|
|
|
|
"""Creates a bound instance method, where the instance is weakly
|
|
|
|
referred.
|
|
|
|
|
|
|
|
This trick is necessary if the bound method is to be attached
|
|
|
|
to that instance's attribute list (e.g. via instance.__dict__),
|
|
|
|
because otherwise a circular reference occurs:
|
|
|
|
|
|
|
|
bound_method -> instance -> bound_method (via __dict__)
|
|
|
|
|
|
|
|
CAVEAT: Know what you are doing! In general, this is a haram trick.
|
|
|
|
We circumvent the standard class type-safety mechanism in python here:
|
|
|
|
if the `method` actually belongs to a completely unrelated class,
|
|
|
|
this routine still accepts it and allow the function to be called.
|
|
|
|
"""
|
|
|
|
# NOTE: This is an identical trick to wpylib.py.im_ref.xbound_im_ref;
|
|
|
|
# the latter (the OO interface) is better because
|
|
|
|
# it does not need function closure, and that the object data is
|
|
|
|
# easier to diagnose.
|
|
|
|
from weakref import ref
|
|
|
|
instance_ref = ref(instance)
|
|
|
|
instance_cls = instance.__class__
|
|
|
|
try:
|
|
|
|
im_func, im_class = method.im_func, method.im_class
|
|
|
|
#im_method = new.instancemethod(im_func, None, instance_cls)
|
|
|
|
except AttributeError:
|
|
|
|
im_func = method
|
|
|
|
# Assume this is a function defined outside a class, which is then
|
|
|
|
# injected into this instance.
|
|
|
|
# The first argument must be the usual `self` argument.
|
|
|
|
return lambda *args, **kwargs: method(instance_ref(), *args, **kwargs)
|
|
|
|
|
|
|
|
return lambda *args, **kwargs: im_func(instance_ref(), *args, **kwargs)
|
|
|
|
|
|
|
|
|
|
|
|
def function_name(f):
|
|
|
|
"""Returns the given name of a function (or callable object)."""
|
|
|
|
try:
|
|
|
|
# Regular function
|
|
|
|
return f.func_name
|
|
|
|
except:
|
|
|
|
pass
|
|
|
|
try:
|
|
|
|
# Instance method
|
|
|
|
return "%s.%s" % (f.im_class, f.im_func.func_name)
|
|
|
|
except:
|
|
|
|
pass
|
|
|
|
# Callable class instance:
|
|
|
|
return f.__class__.__name__
|
|
|
|
|
|
|
|
|