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########################## LICENCE ###############################
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##
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## Copyright (c) 2005, Michele Simionato
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## All rights reserved.
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##
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## Redistributions of source code must retain the above copyright
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## notice, this list of conditions and the following disclaimer.
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## Redistributions in bytecode form must reproduce the above copyright
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## notice, this list of conditions and the following disclaimer in
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## the documentation and/or other materials provided with the
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## distribution.
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## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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## HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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## INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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## BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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## OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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## ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
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## TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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## USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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## DAMAGE.
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"""
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Decorator module, see http://pypi.python.org/pypi/decorator
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for the documentation.
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"""
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__all__ = ["decorator", "FunctionMaker", "partial",
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"deprecated", "getinfo", "new_wrapper"]
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import os, sys, re, inspect, string, warnings
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try:
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from functools import partial
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except ImportError: # for Python version < 2.5
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class partial(object):
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"A simple replacement of functools.partial"
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def __init__(self, func, *args, **kw):
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self.func = func
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self.args = args
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self.keywords = kw
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def __call__(self, *otherargs, **otherkw):
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kw = self.keywords.copy()
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kw.update(otherkw)
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return self.func(*(self.args + otherargs), **kw)
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DEF = re.compile('\s*def\s*([_\w][_\w\d]*)\s*\(')
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# basic functionality
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class FunctionMaker(object):
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"""
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An object with the ability to create functions with a given signature.
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It has attributes name, doc, module, signature, defaults, dict and
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methods update and make.
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"""
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def __init__(self, func=None, name=None, signature=None,
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defaults=None, doc=None, module=None, funcdict=None):
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if func:
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# func can be a class or a callable, but not an instance method
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self.name = func.__name__
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if self.name == '<lambda>': # small hack for lambda functions
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self.name = '_lambda_'
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self.doc = func.__doc__
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self.module = func.__module__
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if inspect.isfunction(func):
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argspec = inspect.getargspec(func)
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self.args, self.varargs, self.keywords, self.defaults = argspec
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for i, arg in enumerate(self.args):
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setattr(self, 'arg%d' % i, arg)
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self.signature = inspect.formatargspec(
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formatvalue=lambda val: "", *argspec)[1:-1]
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self.dict = func.__dict__.copy()
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if name:
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self.name = name
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if signature is not None:
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self.signature = signature
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if defaults:
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self.defaults = defaults
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if doc:
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self.doc = doc
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if module:
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self.module = module
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if funcdict:
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self.dict = funcdict
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# check existence required attributes
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assert hasattr(self, 'name')
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if not hasattr(self, 'signature'):
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raise TypeError('You are decorating a non function: %s' % func)
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def update(self, func, **kw):
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"Update the signature of func with the data in self"
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func.__name__ = self.name
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func.__doc__ = getattr(self, 'doc', None)
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func.__dict__ = getattr(self, 'dict', {})
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func.func_defaults = getattr(self, 'defaults', ())
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callermodule = sys._getframe(3).f_globals.get('__name__', '?')
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func.__module__ = getattr(self, 'module', callermodule)
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func.__dict__.update(kw)
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def make(self, src_templ, evaldict=None, addsource=False, **attrs):
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"Make a new function from a given template and update the signature"
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src = src_templ % vars(self) # expand name and signature
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evaldict = evaldict or {}
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mo = DEF.match(src)
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if mo is None:
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raise SyntaxError('not a valid function template\n%s' % src)
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name = mo.group(1) # extract the function name
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reserved_names = set([name] + [
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arg.strip(' *') for arg in self.signature.split(',')])
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for n, v in evaldict.iteritems():
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if n in reserved_names:
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raise NameError('%s is overridden in\n%s' % (n, src))
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if not src.endswith('\n'): # add a newline just for safety
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src += '\n'
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try:
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code = compile(src, '<string>', 'single')
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exec code in evaldict
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except:
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print >> sys.stderr, 'Error in generated code:'
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print >> sys.stderr, src
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raise
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func = evaldict[name]
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if addsource:
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attrs['__source__'] = src
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self.update(func, **attrs)
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return func
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@classmethod
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def create(cls, obj, body, evaldict, defaults=None,
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doc=None, module=None, addsource=True,**attrs):
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"""
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Create a function from the strings name, signature and body.
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evaldict is the evaluation dictionary. If addsource is true an attribute
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__source__ is added to the result. The attributes attrs are added,
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if any.
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"""
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if isinstance(obj, str): # "name(signature)"
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name, rest = obj.strip().split('(', 1)
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signature = rest[:-1] #strip a right parens
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func = None
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else: # a function
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name = None
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signature = None
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func = obj
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fun = cls(func, name, signature, defaults, doc, module)
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ibody = '\n'.join(' ' + line for line in body.splitlines())
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return fun.make('def %(name)s(%(signature)s):\n' + ibody,
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evaldict, addsource, **attrs)
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def decorator(caller, func=None):
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"""
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decorator(caller) converts a caller function into a decorator;
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decorator(caller, func) decorates a function using a caller.
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"""
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if func is not None: # returns a decorated function
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return FunctionMaker.create(
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func, "return _call_(_func_, %(signature)s)",
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dict(_call_=caller, _func_=func), undecorated=func)
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else: # returns a decorator
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if isinstance(caller, partial):
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return partial(decorator, caller)
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# otherwise assume caller is a function
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f = inspect.getargspec(caller)[0][0] # first arg
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return FunctionMaker.create(
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'%s(%s)' % (caller.__name__, f),
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'return decorator(_call_, %s)' % f,
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dict(_call_=caller, decorator=decorator), undecorated=caller,
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doc=caller.__doc__, module=caller.__module__)
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###################### deprecated functionality #########################
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@decorator
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def deprecated(func, *args, **kw):
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"A decorator for deprecated functions"
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warnings.warn(
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('Calling the deprecated function %r\n'
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'Downgrade to decorator 2.3 if you want to use this functionality')
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% func.__name__, DeprecationWarning, stacklevel=3)
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return func(*args, **kw)
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@deprecated
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def getinfo(func):
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"""
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Returns an info dictionary containing:
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- name (the name of the function : str)
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- argnames (the names of the arguments : list)
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- defaults (the values of the default arguments : tuple)
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- signature (the signature : str)
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- doc (the docstring : str)
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- module (the module name : str)
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- dict (the function __dict__ : str)
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>>> def f(self, x=1, y=2, *args, **kw): pass
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>>> info = getinfo(f)
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>>> info["name"]
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'f'
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>>> info["argnames"]
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['self', 'x', 'y', 'args', 'kw']
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>>> info["defaults"]
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(1, 2)
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>>> info["signature"]
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'self, x, y, *args, **kw'
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"""
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assert inspect.ismethod(func) or inspect.isfunction(func)
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regargs, varargs, varkwargs, defaults = inspect.getargspec(func)
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argnames = list(regargs)
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if varargs:
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argnames.append(varargs)
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if varkwargs:
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argnames.append(varkwargs)
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signature = inspect.formatargspec(regargs, varargs, varkwargs, defaults,
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formatvalue=lambda value: "")[1:-1]
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return dict(name=func.__name__, argnames=argnames, signature=signature,
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defaults = func.func_defaults, doc=func.__doc__,
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module=func.__module__, dict=func.__dict__,
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globals=func.func_globals, closure=func.func_closure)
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@deprecated
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def update_wrapper(wrapper, model, infodict=None):
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"A replacement for functools.update_wrapper"
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infodict = infodict or getinfo(model)
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wrapper.__name__ = infodict['name']
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wrapper.__doc__ = infodict['doc']
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wrapper.__module__ = infodict['module']
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wrapper.__dict__.update(infodict['dict'])
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wrapper.func_defaults = infodict['defaults']
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wrapper.undecorated = model
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return wrapper
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@deprecated
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def new_wrapper(wrapper, model):
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"""
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An improvement over functools.update_wrapper. The wrapper is a generic
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callable object. It works by generating a copy of the wrapper with the
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right signature and by updating the copy, not the original.
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Moreovoer, 'model' can be a dictionary with keys 'name', 'doc', 'module',
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'dict', 'defaults'.
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"""
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if isinstance(model, dict):
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infodict = model
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else: # assume model is a function
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infodict = getinfo(model)
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assert not '_wrapper_' in infodict["argnames"], (
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'"_wrapper_" is a reserved argument name!')
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src = "lambda %(signature)s: _wrapper_(%(signature)s)" % infodict
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funcopy = eval(src, dict(_wrapper_=wrapper))
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return update_wrapper(funcopy, model, infodict)
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