########################## 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 == '': # 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, '', '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)