How to warn about class (name) deprecation
Maybe I could make OldClsName a function which emits a warning (to logs) and constructs the NewClsName object from its parameters (using *args and **kvargs) but it doesn't seem elegant enough (or maybe it is?).
Yup, I think that's pretty standard practice:
def OldClsName(*args, **kwargs):
from warnings import warn
warn("get with the program!")
return NewClsName(*args, **kwargs)
The only tricky thing is if you have things that subclass from OldClsName
- then we have to get clever. If you just need to keep access to class methods, this should do it:
class DeprecationHelper(object):
def __init__(self, new_target):
self.new_target = new_target
def _warn(self):
from warnings import warn
warn("Get with the program!")
def __call__(self, *args, **kwargs):
self._warn()
return self.new_target(*args, **kwargs)
def __getattr__(self, attr):
self._warn()
return getattr(self.new_target, attr)
OldClsName = DeprecationHelper(NewClsName)
I haven't tested it, but that should give you the idea - __call__
will handle the normal-instantation route, __getattr__
will capture accesses to the class methods & still generate the warning, without messing with your class heirarchy.
Please have a look at warnings.warn
.
As you'll see, the example in the documentation is a deprecation warning:
def deprecation(message):
warnings.warn(message, DeprecationWarning, stacklevel=2)