Kent:
I forgot to mention that no coping is allowed. Your two options essentially are doing copying of the b.
Furthermore, let's say, I don't even know the inside details of B, for example, I subclass the socket.socket,
and I got a client socket after it accepting an incoming connection, and I want to use the newly gotten client
socket to create an instance of the subClass. Following is the way normally I would do,
but I don't know the abnormal case---gotten an client socket (instance of socket.socket) and trying to use it
to create an instance of MySocket (subclass of socket.socket).
import socket
class MySocket(socket.socket):
''' my special socket '''
def __init__(self, family, sock_type):
socket.socket.__init__(self, family, socket_type)
self.extra="blah blah blah"
Hope this help clarifying my intent.
On 2/13/06, Kent Johnson <[EMAIL PROTECTED]> wrote:
Kenny Li wrote:
> *class B(object): *
> * ''' the baseClass '''*
> * def __init__(self, arg1, arg2):*
> * self.a1=arg1*
> * self.a2=arg2*
> * *
> *class C(B): *
> * ''' C is subClass of B '''*
> * def __init__(self, arg1, arg2):*
> * B.__init__(self, arg1, arg2)*
> * self.extra="blah blah blah"*
> **
> *if __name__ == '__main__':*
> * # Now, I ran into a situation, where I don't have the values
> of "arg1 and arg2", *
> * # but I do have an instance of baseClass (B), called b. *
> **
> * # How do I write the class C [for example, its
> __new__(cls...) static method] to enable me to do the following?*
> * c=C(b) # <<< This is what I want.*
Two options:
1. Just pass b.a1 and b.a2 to the C constructor:
c = C(b.a1, b.a2)
A little clumsy but it works.
2. Write C.__init__() to accept either form:
def __init__(self, arg1, arg2=None):
if isinstance(arg1, B):
arg1, arg2 = arg1.a1, arg1.a2
# the rest as before
Kent
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