How to use readline interactively?

[John Farrell]

"Thomas A. Bryan" wrote:
> John Farrell wrote:
> > import sys
> > while 1:
> >     print "> ",
> >     s = sys.stdin.readline()
> >     if s[-1] == '\n': s = s[:-1]
> >     if len(s) == 0: break
> >     print "Hello " + s

> You could use sys.stdout.write() in one or both places.
> 
> What you're seeing is the comma from the line
> print "> ",
> It is output as a space at the front of your
> print "Hello" + s

Of course, that makes sense. Thank you for explaining it.

> P.S. I'm sure you're just posting a code fragement, but I
> used EOF to get out of the while loop (like any good Python
> programmer :), and the code snippet died with an uncaught
> IndexError exception.

That's a habit I never got into, but I do remember spending hours
trying to handle EOF in C or maybe Pascal when I was at Uni. I guess
that's why I never got into the habit, because it broke my programs :-).
I find it mildly distressing that the user can arbitrarily tell the
program that it's not getting any more input, it would be kinder to
just hit Ctrl-Break and put the poor thing out of its misery.

The revised code snippet is:

import sys
while 1:
    sys.stdout.write("> ")
    s = sys.stdin.readline()
    if len(s) > 0 and s[-1] == '\n': s = s[:-1]
    if len(s) == 0: break
    sys.stdout.write("Hello " + s + '\n')

which works just like I want it to, and will even handle EOF. I seem
to remember already doing this in my proper app.

John