On 12/20/2012 5:52 PM, Jens Thoms Toerring wrote:
You are rather likely right and I probably should have written:
"I don't see any way to pass that variable to the object that
is supposed to use it". Perhaps you have an idea how it could
be done correctly when I explain the complete picture: I'm
writing a TCP server, based on SocketServer:
server = SocketServer.TCPServer((192.168.1.10, 12345), ReqHandler)
where ReqHandler is the name of a class derived from
SocketServer.BaseRequestHandler
You misunderstood the doc. You pass the class, not the name of the class.
From 21.19.4.1. socketserver.TCPServer Example
server = socketserver.TCPServer((HOST, PORT), MyTCPHandler)
MyTCPHandler is the actual class. What gets 'passed' at the C level in
CPython is a reference that class that TCPServer can use to call it, but
conceptually, at the Python level, think of it as the class. In the
code, you enter the name without quotes and that expression evaluates to
the (reference to the) class that gets passed.
If the signature required the name, the example would have had
'MyTCPHandler', with the quotes, to pass the name as a string.
Very few builtin functions require names as strings. open('filename'),
somebytes.encode(encoding='encoding-name', errors =
'error-handler-name') are two that come to mind. Notice that these are
situations where requiring a non-string object would be inconvenient at
best.
class ReqHandler(SocketServer.BaseRequestHandler):
...
A new instance of this class is gernerated for each connection
request to the server. In the call that creates the server I can
only specify the name of the class but no arguments to be passed
Code those arguments directly into the handle method of your version of
MyTCPhandler. Or if you need to override multiple methods and use the
same values in multiple methods, override __init__ and add self.x =
x-value statements.
--
Terry Jan Reedy
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