Oddity question

[Mariano Corsunsky]

Sorry, my mistake. I forgot the "self." when I wrote the question...

Here, again....

 I was fooling around with sockets last night, using a thread to deal with
the read part and another method to do the print.

 like this:

def thread_read (self):
    while 1:
        self.buf=self.buf+self.my_socket.recv (8)

def print_buf(self):
    if self.buf:
        print "bufeer-->",self.buf
        self.buf='""

But, what happened to me was that the -buf = ""- line seemed to be not
working  because I got outputs like this

buffer->a
buffer->ab
buffer->abpleasework
buffer->abpleaseworkpleaseflush!


 So, I dont know why I changed thread_read function to:

def thread_read (self):
    while 1:
        aux=3Dself.my_socket.recv (8)
        self.buf=3Dself.buf+aux


And this version worked properly..... but I still do not know why.
To me, I've only split the line in two, using an auiliar variable... but
THAT made the trick!
why?
 WHY?
   W H Y?

(thanks for answers)
>
>
> --
"mcherm" <mcherm at destiny.com> wrote in message
news:3C7BF84F.1090306 at destiny.com...
> > I was fooling around with sockets last night, using a thread to deal =
> > with the read part and another method to do the print.
> >
> > like this:
> >
> > def thread_read (self):
> >   while 1:
> >     self.buf=3Dself.buf+self.my_socket.recv (8)
> >
> > def print_buf(self):
> >   if buf:
> >     print "bufeer-->",buf
> >     buf=3D'""
> >
> > But, what happened to me was that the -buf =3D ""- line seemed to be not
=
> > working     [...]
>
> > So, I dont know why I changed thread_read function to:
> >
> >   while 1:
> >     aux=3Dself.my_socket.recv (8)
> >     self.buf=3Dself.buf+aux
> >
> > And this version worked properly..... but I still do not know why.
>
> Well, I can't tell exactly what you were doing here (try sending plain
> text instead of html... it doesn't get mangled as much), but I do see
> one thing. In the example that doesn't work you have a line 'buf=""' at
> the end of a function or method, while the example that DOES work has
> 'self.buf=self.buf+aux' inside a loop.
>
> If buf is a local variable, then 'buf=""' at the end of a function will
> only modify the local variable and do nothing to the actual buffer
> (strings are immutable in Python). Modifying self.buf in a loop will not
> be lost in this fashion.
>
> Does that help any?
>
> -- Michael Chermside
>
>
>
>
>
> --
> http://mail.python.org/mailman/listinfo/python-list


--- for a personal reply use: "Mariano Corsunsky" <morsa at core-sdi.com>