219 lines
7.6 KiB
Python
219 lines
7.6 KiB
Python
"""
|
|
Decorator module by Michele Simionato <michelesimionato@libero.it>
|
|
Copyright Michele Simionato, distributed under the terms of the BSD License (see below).
|
|
http://www.phyast.pitt.edu/~micheles/python/documentation.html
|
|
|
|
Included in NLTK for its support of a nice memoization decorator.
|
|
"""
|
|
from __future__ import print_function
|
|
__docformat__ = 'restructuredtext en'
|
|
|
|
## The basic trick is to generate the source code for the decorated function
|
|
## with the right signature and to evaluate it.
|
|
## Uncomment the statement 'print >> sys.stderr, func_src' in _decorator
|
|
## to understand what is going on.
|
|
|
|
__all__ = ["decorator", "new_wrapper", "getinfo"]
|
|
|
|
import sys
|
|
|
|
# Hack to keep NLTK's "tokenize" module from colliding with the "tokenize" in
|
|
# the Python standard library.
|
|
old_sys_path = sys.path[:]
|
|
sys.path = [p for p in sys.path if "nltk" not in p]
|
|
import inspect
|
|
sys.path = old_sys_path
|
|
|
|
try:
|
|
set
|
|
except NameError:
|
|
from sets import Set as set
|
|
|
|
def getinfo(func):
|
|
"""
|
|
Returns an info dictionary containing:
|
|
- name (the name of the function : str)
|
|
- argnames (the names of the arguments : list)
|
|
- defaults (the values of the default arguments : tuple)
|
|
- signature (the signature : str)
|
|
- doc (the docstring : str)
|
|
- module (the module name : str)
|
|
- dict (the function __dict__ : str)
|
|
|
|
>>> def f(self, x=1, y=2, *args, **kw): pass
|
|
|
|
>>> info = getinfo(f)
|
|
|
|
>>> info["name"]
|
|
'f'
|
|
>>> info["argnames"]
|
|
['self', 'x', 'y', 'args', 'kw']
|
|
|
|
>>> info["defaults"]
|
|
(1, 2)
|
|
|
|
>>> info["signature"]
|
|
'self, x, y, *args, **kw'
|
|
"""
|
|
assert inspect.ismethod(func) or inspect.isfunction(func)
|
|
if sys.version_info[0] >= 3:
|
|
argspec = inspect.getfullargspec(func)
|
|
else:
|
|
argspec = inspect.getargspec(func)
|
|
regargs, varargs, varkwargs, defaults = argspec[:4]
|
|
argnames = list(regargs)
|
|
if varargs:
|
|
argnames.append(varargs)
|
|
if varkwargs:
|
|
argnames.append(varkwargs)
|
|
signature = inspect.formatargspec(regargs, varargs, varkwargs, defaults,
|
|
formatvalue=lambda value: "")[1:-1]
|
|
|
|
# pypy compatibility
|
|
if hasattr(func, '__closure__'):
|
|
_closure = func.__closure__
|
|
_globals = func.__globals__
|
|
else:
|
|
_closure = func.func_closure
|
|
_globals = func.func_globals
|
|
|
|
return dict(name=func.__name__, argnames=argnames, signature=signature,
|
|
defaults = func.__defaults__, doc=func.__doc__,
|
|
module=func.__module__, dict=func.__dict__,
|
|
globals=_globals, closure=_closure)
|
|
|
|
# akin to functools.update_wrapper
|
|
def update_wrapper(wrapper, model, infodict=None):
|
|
infodict = infodict or getinfo(model)
|
|
wrapper.__name__ = infodict['name']
|
|
wrapper.__doc__ = infodict['doc']
|
|
wrapper.__module__ = infodict['module']
|
|
wrapper.__dict__.update(infodict['dict'])
|
|
wrapper.__defaults__ = infodict['defaults']
|
|
wrapper.undecorated = model
|
|
return wrapper
|
|
|
|
def new_wrapper(wrapper, model):
|
|
"""
|
|
An improvement over functools.update_wrapper. The wrapper is a generic
|
|
callable object. It works by generating a copy of the wrapper with the
|
|
right signature and by updating the copy, not the original.
|
|
Moreovoer, 'model' can be a dictionary with keys 'name', 'doc', 'module',
|
|
'dict', 'defaults'.
|
|
"""
|
|
if isinstance(model, dict):
|
|
infodict = model
|
|
else: # assume model is a function
|
|
infodict = getinfo(model)
|
|
assert not '_wrapper_' in infodict["argnames"], (
|
|
'"_wrapper_" is a reserved argument name!')
|
|
src = "lambda %(signature)s: _wrapper_(%(signature)s)" % infodict
|
|
funcopy = eval(src, dict(_wrapper_=wrapper))
|
|
return update_wrapper(funcopy, model, infodict)
|
|
|
|
# helper used in decorator_factory
|
|
def __call__(self, func):
|
|
return new_wrapper(lambda *a, **k : self.call(func, *a, **k), func)
|
|
|
|
def decorator_factory(cls):
|
|
"""
|
|
Take a class with a ``.caller`` method and return a callable decorator
|
|
object. It works by adding a suitable __call__ method to the class;
|
|
it raises a TypeError if the class already has a nontrivial __call__
|
|
method.
|
|
"""
|
|
attrs = set(dir(cls))
|
|
if '__call__' in attrs:
|
|
raise TypeError('You cannot decorate a class with a nontrivial '
|
|
'__call__ method')
|
|
if 'call' not in attrs:
|
|
raise TypeError('You cannot decorate a class without a '
|
|
'.call method')
|
|
cls.__call__ = __call__
|
|
return cls
|
|
|
|
def decorator(caller):
|
|
"""
|
|
General purpose decorator factory: takes a caller function as
|
|
input and returns a decorator with the same attributes.
|
|
A caller function is any function like this::
|
|
|
|
def caller(func, *args, **kw):
|
|
# do something
|
|
return func(*args, **kw)
|
|
|
|
Here is an example of usage:
|
|
|
|
>>> @decorator
|
|
... def chatty(f, *args, **kw):
|
|
... print("Calling %r" % f.__name__)
|
|
... return f(*args, **kw)
|
|
|
|
>>> chatty.__name__
|
|
'chatty'
|
|
|
|
>>> @chatty
|
|
... def f(): pass
|
|
...
|
|
>>> f()
|
|
Calling 'f'
|
|
|
|
decorator can also take in input a class with a .caller method; in this
|
|
case it converts the class into a factory of callable decorator objects.
|
|
See the documentation for an example.
|
|
"""
|
|
if inspect.isclass(caller):
|
|
return decorator_factory(caller)
|
|
def _decorator(func): # the real meat is here
|
|
infodict = getinfo(func)
|
|
argnames = infodict['argnames']
|
|
assert not ('_call_' in argnames or '_func_' in argnames), (
|
|
'You cannot use _call_ or _func_ as argument names!')
|
|
src = "lambda %(signature)s: _call_(_func_, %(signature)s)" % infodict
|
|
# import sys; print >> sys.stderr, src # for debugging purposes
|
|
dec_func = eval(src, dict(_func_=func, _call_=caller))
|
|
return update_wrapper(dec_func, func, infodict)
|
|
return update_wrapper(_decorator, caller)
|
|
|
|
def getattr_(obj, name, default_thunk):
|
|
"Similar to .setdefault in dictionaries."
|
|
try:
|
|
return getattr(obj, name)
|
|
except AttributeError:
|
|
default = default_thunk()
|
|
setattr(obj, name, default)
|
|
return default
|
|
|
|
@decorator
|
|
def memoize(func, *args):
|
|
dic = getattr_(func, "memoize_dic", dict)
|
|
# memoize_dic is created at the first call
|
|
if args in dic:
|
|
return dic[args]
|
|
else:
|
|
result = func(*args)
|
|
dic[args] = result
|
|
return result
|
|
|
|
|
|
########################## LEGALESE ###############################
|
|
|
|
## Redistributions of source code must retain the above copyright
|
|
## notice, this list of conditions and the following disclaimer.
|
|
## Redistributions in bytecode form must reproduce the above copyright
|
|
## notice, this list of conditions and the following disclaimer in
|
|
## the documentation and/or other materials provided with the
|
|
## distribution.
|
|
|
|
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
## HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
## INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
## BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
## OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
|
|
## ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
|
|
## TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
|
|
## USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
|
|
## DAMAGE.
|