(Looks like you posted privately to me; should use Reply-all. I'm
copying entire message here so others can add to my comments)
Mac Ryan wrote:
On Wed, 2009-08-26 at 15:46 -0400, Dave Angel wrote:
So define a classmethod to finish the job, and invoke it later
class Employee(object):
@classmethod
def finish(cls):
cls.__storm_table__ = "employee"
cls.company_id = []
cls.company = Company.id #where Company is a forward
reference
del cls.finish #remove this method so it won't be called a
second time
class Company:
id = 42
Employee.finish() #This finishes initializing the class
help(Employee)
print Employee.company_id
First things first, thank you Wayne, Kent and Dave for your extensive
and complementary explanations. As many things in python, what it seemed
obscure at first now - with your help - seems perfectly obvious.
Second thing: the example that Dave gave me and that I left quoted above
makes use of decorators, but this is something that I still do not
understand. I believe I got a grasp of the concept of metaclasses, to
which the concept of decorator seems to be related, but the official
documentation is a a bit obscure for me.
I don't want to steal your time asking for an explanation that probably
is already somewhere out there, but my google searches did not return
anything useful (I assume I am using the wrong keywords here), so if you
have a good pointer for me, I would be very grateful. :)
Mac.
Decorators are syntactic sugar to save typing; what they accomplish can
always be done another way, but generally not as readable.
#somebody (eg., Python library) defines a function that takes a function
as parameter, and returns a function, generally a different one related
to the first
def mydecorator(funct):
....
return newfunct
class myclass(object):
@mydecorator
def mymethod(self, arg1, arg2):
...
Instead of the @syntax, we could also have written:
class myclass(object):
def mymethod(self, arg1, arg2)
....
mymethod = mydecorator(mymethod) #this call happens
when the class is being created
Now there are a couple of decorators that are in the standard library
that everyone should know about: classmethod() and staticmethod().
They wrap a method in a new one (which ends up having the same name),
such that the first argument is either eaten (staticmethod), or changed
to a class (classmethod).
Hope that was sufficient detail.
DaveA
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