Thanks very much to Harlin Seritt. Your example is really helpful to me. I read some more docs on python oop and I am more clear now. But when I try to understand Decorators for Functions and Methods in PEP 318, I got puzzled. How do Decorators work?
I think decorator is a function which return a function, is this right? e.g. The decorator below if from http://www.python.org/peps/pep-0318.html#id1. def accepts(*types): def check_accepts(f): assert len(types) == f.func_code.co_argcount def new_f(*args, **kwds): for (a, t) in zip(args, types): assert isinstance(a, t), \ "arg %r does not match %s" % (a,t) return f(*args, **kwds) new_f.func_name = f.func_name return new_f return check_accepts After I saw all the examples, I concluded that every decorator must define an inner function which takes only one argument, the function to decorate. Is this right? On 5/18/05, Harlin Seritt <[EMAIL PROTECTED]> wrote: > could ildg wrote: > > I have learned python for over a month. > > I heard that it was very easy to learn, but when I tried to know OO > of python, > > I found it really weird, some expressions seem very hard to > understand, > > and I can't find enough doc to know any more about it. > > So, I wonder how did you master python? And where to find some cool > docs? > > > > Thanks. > > I think I know what you mean. When I first started trying to learn the > OOP aspect of Python I thought it was strange since I had started with > OOP on Java and C++. Nonetheless, once you get the hang of it, OOP will > make way more sense than all of the complications of Java and C++ class > implementations. Let me give you a quick example of what I'm talking > about: > > class Animal: > def eats(self): > print 'The animal eats.' > def walks(self): > print 'The animal walks.' > > """Here the class Dog instantiates the class Animal. 'Dog' will 'do' > whatever 'Animal' does plus some other things which we will describe in > this class code.""" > class Dog(Animal): > """#the self keyword means that this function will be a class > function""" > def communicate(self): > print 'The dog barks.' > > """# __init__ function defines what # #will happen as soon as this > class is instantiated. Also, the overloaded variable designators (color > = None, fur = None) allow the instantiator to optionally define these > variables when called from elsewhere.""" > > def __init__(self, color=None, fur=None): > """# this time self will designate the variable 'color' # as a > class variable.""" > self.color = color > self.fur = fur > > if __name__ == '__main__': > sparky = Dog(color="White", fur="Short") > sparky.communicate() > print sparky.color > print sparky.fur > print sparky.eats() # Here sparky will access 'Animal' methods > that 'Dog' inherited. > print sparky.walks() # Another method originating from the 'Animal' > class. > > What happens if you don't use 'self' inside your class code? You won't > be able to access it within the class outside of the method where you > initialized it. For instance, if you don't designate color with self > then you can only use the 'color' variable within the __init__() > method. This is useful whenever you want to use 'color' as a private > variable. > > The same also goes for methods. Hopefully, you see how useful this can > be down the road. This way you won't have to use variable/method access > modifiers like Public, Private, Protected and so forth. If this doesn't > make sense or you want more clarity, please let me know. > > Good luck, > > Harlin Seritt > > -- http://mail.python.org/mailman/listinfo/python-list
