+"""
+Decorator module, see
+http://www.phyast.pitt.edu/~micheles/python/documentation.html
+for the documentation and below for the licence.
+"""
+
+## 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 inspect, sys
+
+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)
+ 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)
+
+# akin to functools.update_wrapper
+def update_wrapper(wrapper, model, infodict=None):
+ infodict = infodict or getinfo(model)
+ try:
+ wrapper.__name__ = infodict['name']
+ except: # Python version < 2.4
+ pass
+ wrapper.__doc__ = infodict['doc']
+ wrapper.__module__ = infodict['module']
+ wrapper.__dict__.update(infodict['dict'])
+ wrapper.func_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):
+ infodict = getinfo(func)
+ for name in ('_func_', '_self_'):
+ assert not name in infodict["argnames"], (
+ '%s is a reserved argument name!' % name)
+ src = "lambda %(signature)s: _self_.call(_func_, %(signature)s)"
+ new = eval(src % infodict, dict(_func_=func, _self_=self))
+ return update_wrapper(new, func, infodict)
+
+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)
+
+if __name__ == "__main__":
+ import doctest; doctest.testmod()
+
+########################## 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.
fnp / wolnelektury.git / blobdiff