What is the proper way to decorate the methods of a class?

[jmkacz]

This question is involves v0.8.1 versus v0.9.0, and class decoration.

With v0.8.1 and no decorator library, the following worked. Upgrading to v0.9.0 and installing the decorator library fails, because the behavior of the fallback decorator logic from v0.8.1 is different from the behavior of the decorator library.

What is the proper way to decorate the methods of a class, using the retry library?

import itertools
from retry import retry
from sailthru.sailthru_client import SailthruClient
from sailthru.sailthru_error import SailthruClientError

RETRIES_TRIES = 20
RETRIES_DELAY = 0.5
RETRIES_MAX_DELAY = 1.0
RETRIES_BACKOFF = 2
RETRIES_JITTER = (0, 1)

# taken from http://stackoverflow.com/a/6307868
def for_all_methods(decorator):
        def decorate(cls):
                # Collect all methods from the given class, and the classes
                # it inherits from. Then, discard "magic" methods.
                attrs = [attr for attr in itertools.chain(*[other.__dict__.keys() for other in cls.__mro__]) if not (attr.startswith('__') and attr.endswith('__'))]
                for attr in attrs:
                        if callable(getattr(cls, attr)):
                                setattr(cls, attr, decorator(getattr(cls, attr)))
                return cls
        return decorate

@for_all_methods(retry(SailthruClientError, RETRIES_TRIES, RETRIES_DELAY, RETRIES_MAX_DELAY, RETRIES_BACKOFF, RETRIES_JITTER))
class RobustSailthruClient(SailthruClient):
        pass

Traceback (most recent call last):
  File "foo.py", line 30, in <module>
    class RobustSailthruClient(SailthruClient):
  File "foo.py", line 25, in decorate
    setattr(cls, attr, decorator(getattr(cls, attr)))
  File "<string>", line 2, in retry_decorator
  File "/home/jon/.virtualenvs/ei.new/lib/python2.6/site-packages/decorator.py", line 213, in decorator
    evaldict, __wrapped__=func)
  File "/home/jon/.virtualenvs/ei.new/lib/python2.6/site-packages/decorator.py", line 196, in create
    self = cls(func, name, signature, defaults, doc, module)
  File "/home/jon/.virtualenvs/ei.new/lib/python2.6/site-packages/decorator.py", line 131, in __init__
    raise TypeError('You are decorating a non function: %s' % func)
TypeError: You are decorating a non function: <unbound method RobustSailthruClient.cancel_blast>

[jmkacz]

Given that SailthruClient is coming from a library I pip installed (don't have the source in my code tree).

Is it the case that I would have to fork the library and place it before each function?

[invl]

Does v0.8.1 + decorator library work?

[jmkacz]

v0.8.1 + decorator fails the same way

[jmkacz]

v0.8.1 or v0.9.0 w/o decorator, and thus failing back to https://github.com/invl/retry/blob/0.8.1/retry/compat.py succeeds

[invl]

I don't think retry library is responsible for this, but you could try to change setattr(cls, attr, decorator(getattr(cls, attr))) to setattr(cls, attr, decorator(getattr(cls, attr).im_func))

[invl]

Close due to inactivity.

[janani-s]

@invl That worked, thanks!