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########################## LICENCE ###############################
## 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.
"""
Decorator module, see http://pypi.python.org/pypi/decorator
for the documentation.
"""
__all__ = ["decorator", "FunctionMaker", "deprecated", "getinfo", "new_wrapper"]
import os, sys, re, inspect, warnings
DEF = re.compile('\s*def\s*([_\w][_\w\d]*)\s*\(')
# basic functionality
class FunctionMaker(object):
"""
An object with the ability to create functions with a given signature.
It has attributes name, doc, module, signature, defaults, dict and
methods update and make.
"""
def __init__(self, func=None, name=None, signature=None,
defaults=None, doc=None, module=None, funcdict=None):
if func:
# func can also be a class or a callable, but not an instance method
self.name = func.__name__
if self.name == '<lambda>': # small hack for lambda functions
self.name = '_lambda_'
self.doc = func.__doc__
self.module = func.__module__
if inspect.isfunction(func):
self.signature = inspect.formatargspec(
formatvalue=lambda val: "", *inspect.getargspec(func))[1:-1]
self.defaults = func.func_defaults
self.dict = func.__dict__.copy()
if name:
self.name = name
if signature is not None:
self.signature = signature
if defaults:
self.defaults = defaults
if doc:
self.doc = doc
if module:
self.module = module
if funcdict:
self.dict = funcdict
# check existence required attributes
assert hasattr(self, 'name')
if not hasattr(self, 'signature'):
raise TypeError('You are decorating a non function: %s' % func)
def update(self, func, **kw):
"Update the signature of func with the data in self"
func.__name__ = self.name
func.__doc__ = getattr(self, 'doc', None)
func.__dict__ = getattr(self, 'dict', {})
func.func_defaults = getattr(self, 'defaults', None)
callermodule = sys._getframe(3).f_globals.get('__name__', '?')
func.__module__ = getattr(self, 'module', callermodule)
func.__dict__.update(kw)
def make(self, src_templ, evaldict=None, addsource=False, **attrs):
"Make a new function from a given template and update the signature"
src = src_templ % vars(self) # expand name and signature
evaldict = evaldict or {}
mo = DEF.match(src)
if mo is None:
raise SyntaxError('not a valid function template\n%s' % src)
name = mo.group(1) # extract the function name
reserved_names = set([name] + [
arg.strip(' *') for arg in self.signature.split(',')])
for n, v in evaldict.iteritems():
if n in reserved_names:
raise NameError('%s is overridden in\n%s' % (n, src))
if not src.endswith('\n'): # add a newline just for safety
src += '\n'
try:
code = compile(src, '<string>', 'single')
exec code in evaldict
except:
print >> sys.stderr, 'Error in generated code:'
print >> sys.stderr, src
raise
func = evaldict[name]
if addsource:
attrs['__source__'] = src
self.update(func, **attrs)
return func
def decorator(caller, func=None):
"""
decorator(caller) converts a caller function into a decorator;
decorator(caller, func) decorates a function using a caller.
"""
if func is None: # returns a decorator
fun = FunctionMaker(caller)
first_arg = inspect.getargspec(caller)[0][0]
src = 'def %s(%s): return _call_(caller, %s)' % (
caller.__name__, first_arg, first_arg)
return fun.make(src, dict(caller=caller, _call_=decorator),
undecorated=caller)
else: # returns a decorated function
fun = FunctionMaker(func)
src = """def %(name)s(%(signature)s):
return _call_(_func_, %(signature)s)"""
return fun.make(src, dict(_func_=func, _call_=caller), undecorated=func)
###################### deprecated functionality #########################
@decorator
def deprecated(func, *args, **kw):
"A decorator for deprecated functions"
warnings.warn(
('Calling the deprecated function %r\n'
'Downgrade to decorator 2.3 if you want to use this functionality')
% func.__name__, DeprecationWarning, stacklevel=3)
return func(*args, **kw)
@deprecated
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)
regargs, varargs, varkwargs, defaults = inspect.getargspec(func)
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]
return dict(name=func.__name__, argnames=argnames, signature=signature,
defaults = func.func_defaults, doc=func.__doc__,
module=func.__module__, dict=func.__dict__,
globals=func.func_globals, closure=func.func_closure)
@deprecated
def update_wrapper(wrapper, model, infodict=None):
"A replacement for functools.update_wrapper"
infodict = infodict or getinfo(model)
wrapper.__name__ = infodict['name']
wrapper.__doc__ = infodict['doc']
wrapper.__module__ = infodict['module']
wrapper.__dict__.update(infodict['dict'])
wrapper.func_defaults = infodict['defaults']
wrapper.undecorated = model
return wrapper
@deprecated
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)
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