WakeBdr schrieb:
> I'm writing a class that will query a database for some data and return
> the result to the caller. I need to be able to return the result of
> the query in several different ways: list, xml, dictionary, etc. I was
> wondering if I can use decorators to accomplish this.
>
> For instance, I have the following method
>
> def getUsers(self, params):
> return users.query(dbc)
>
> To get the appropriate return types, I also have these methods. I have
> these convenience methods for every query method in my class.
>
> def getUsersAsXML(self, params):
> return self._toXML(self.getUsers(params))
> def getUsersAsDict(self, params):
> return self._toDict(self.getUsers(params))
> def getUsersAsList(self, params):
> return self._toList(self.getUsers(params))
>
> Instead of creating these three methods for every query method, is
> there a way to use decorators to manipulate the return type. I'd still
> like to have the caller use getUsersAsXML, I just don't want to write
> the AsXML methods for every query method. So the decorator would
> essentially create the convenience methods instead of me coding them.
>
> One solution that I don't want to use is passing a variable into the
> query method that determines the return type. This is what I don't
> want to do.
> def getUsers(self, params, returnType):
>
> Any ideas on how I can accomplish this?
Use a metaclass.
class Magic(type):
def __new__(cls, name, bases, d):
for name, function in d.items():
try:
function._marked
def toXML(self, *args, **kwargs):
return self._toXML(function(self, *args, **kwargs))
def toFOO(self, *args, **kwargs):
return self._toFOO(function(self, *args, **kwargs))
d[name + "XML"] = toXML
d[name + "FOO"] = toFOO
except AttributeError:
pass
return type(name, bases, d)
def mark(f):
f._marked = True
return f
class MyClass(object):
__metaclass__ = Magic
def _toXML(self, value):
return "Look Ma, its XML! %r" % value
def _toFOO(self, value):
return "Look Ma, its FOO! %r" % value
@mark
def someMethod(self):
return "Its the data, son"
o = MyClass()
print o.someMethod()
print o.someMethodXML()
print o.someMethodFOO()
Diez
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