Hi, Thanks again for all the helping me understand the details of
decorators.
I put together a class to create decorators that could make them a lot
easier to use.
It still has a few glitches in it that needs to be addressed.
(1) The test for the 'function' object needs to not test for a string
but an object type instead.
(2) If the same decorator instance is stacked, it will get locked in a
loop. But stacking different instances created from the same
decorator object works fine.
(3) It has trouble if a decorator has more than one argument.
But I think all of these things can be fixed. Would this be something
that could go in the builtins library? (After any issues are fixed
first of course.)
When these are stacked, they process all the prepossess's first, call
the decorator, then process all the postprocess's. It just worked out
that way, which was a nice surprise and makes this work a bit
different than the standard decorators.
Cheers,
Ron
#---start---
class Decorator(objec t):
"""
Decorator - A class to make decorators with.
self.function - name of function decorated.
self.arglist - arguments of decorator
self.preprocess - over ride to preprocess function arguments.
self.postproces s - over ride to postprocess function
return value.
Example use:
class mydecorator(Dec orate):
def self.preprocess (self, args):
# process args
return args
def self.postproces s(self, results):
# process results
return results
deco = mydecorator()
@deco
def function(args):
# function body
return args
"""
function = None
arglist = []
def __call__(self, arg):
self.arglist.ap pend(arg)
def _wrapper( args):
pre_args = self.preprocess (args)
result = self.function(p re_args)
return self.postproces s(result)
if 'function' in str(arg):
self.arglist = self.arglist[:-1]
self.function = arg
return _wrapper
return self
def preprocess(self , args):
return args
def postprocess(sel f, result):
return result
class mydecorator(Dec orater):
def preprocess(self , args):
args = 2*args
return args
def postprocess(sel f, args):
args = args.upper()
args = args + str(self.arglis t[0])
return args
deco = mydecorator()
@deco('xyz')
def foo(text):
return text
print foo('abc')
#---end---
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