I guess I did not emphasize enough that I was just starting to think through this. The code I posted yesterday was more in the way of exploratory code, trying to understand how to implement inheritance, using new-style classes (I am trying to integrate the work with Python 3 at home as much as possible with what I am forced to in Python 2.4 at work where I have no choices as to Python version.).
On Fri, Jun 17, 2016 at 10:31 AM, Steven D'Aprano <st...@pearwood.info> wrote: > Some futher thoughts: > > On Thu, Jun 16, 2016 at 10:38:13AM -0500, boB Stepp wrote: >> class FTPFiles(FTP, object): >> """FTP files to Windows server location(s).""" >> >> def __init__(self, host=server_ip, user=user, passwd=passwd): >> """Initialize FTPFiles object. Normally the defaults will be >> used.""" >> >> super(FTPFiles, self).__init__(host, user, passwd) >> self.host = host >> self.user = user >> self.passwd = passwd > > Do you actually need to record these? Once they're used to establish a > connection and login, what are they for? No, I was just spelling everything out for myself while I was trying to figure out why my original code was not working. All the things I said I "learned" were not in my earlier versions. These lines have already been excised as I am getting closer to something I might actually want to implement. Also, now that I have had the opportunity to play around with inheritance, I don't see any need to specialize the FTP class as I mention in my response to Alan I just sent out. > >> def print_welcome_msg(self): >> """Print welcome message sent by FTP server.""" >> print self.getwelcome() > > The getwelcome method already prints the message, which is a bad design. > But only if debugging is true. So I would approach this in one of two > ways: The only point of this method was to ensure that I was actually connected to my server. During earlier versions, things were acting weird and I was not understanding what was going on. So I wanted to be certain I was in fact connected; it turned out I was not! This also has been excised today. > (1) Delegate to the existing getwelcome method: > > def print_welcome_msg(self): > save_flag = self.debugging > self.debugging = True > try: > x = self.getwelcome() # prints the msg > finally: > self.debugging = save_flag > > > (2) Re-implement the print functionality. > > def print_welcome_msg(self): > print "*welcome*", self.welcome > > > (3) If you really want to be paranoid, use: > > print "*welcome*", self.sanitize(self.welcome) > > > although I don't think it's likely to make any real difference in > practice. > > (The sanitize method makes a feeble attempt to hide the password.) Some interesting ideas to aid debugging. Thanks! >> What I learned today: >> >> 1) FTP from ftplib appears to be an old-style class. >> >> 2) I can't just use "class FTPFiles(FTP)" or I will be using old-style >> classes. > > Is this a problem? Old-style classes are good enough for many purposes. Not really. I am just trying to consolidate the studies I am doing at home with Python 3 as much as I can when I am working with Python 2. >> 3) I need to use "class FTPFiles(FTP, object)" to use new-style >> classes and "object" must come AFTER "FTP". >> >> 4) I have to use "super(FTPFiles, self).__init__(host, user, passwd)" >> or I cannot successfully inherit from the FTP() class. Also, "self" >> apparently must come AFTER "FTPFiles" in the super expression. > > For old-style classes, don't use super because it doesn't work. Instead > just write: > > FTP.__init__(self, host, user, passwd) Yeah, if I just stuck to old-style, things would have been easier. > That means that you cannot engage in multiple inheritence with new-style > classes, but MI is a serious pain to get right, and 99% of the time it > is overkill, so you're not missing much. Right now just the simpler OOP stuff is a "serious pain" while I am still in the relatively early stages of learning. ~(:>)) boB _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
