Re: Running Python Demo on the Web?
On Wed, 2011-09-07 at 18:40:23 -0700, Laurent wrote: Neat. But I can see some print(x) and some print x. What is the Python version? See: http://docs.python.org/release/3.2.2/whatsnew/3.0.html#print-is-a-function http://www.python.org/dev/peps/pep-3105/ -- Sahil Tandon sa...@freebsd.org -- http://mail.python.org/mailman/listinfo/python-list
Re: idiomatic analogue of Perl's: while () { ... }
Dennis Lee Bieber wrote: On Thu, 1 Sep 2011 00:56:50 -0400, Sahil Tandonsa...@freebsd.org # process input, line-by-line, and print responses after parsing input while 1: rval = parse(raw_input()) if rval == None: There is only ONE None object so the preferred method is if rval is None: Understood; thanks for that enlightenment. Note: I don't see any exit handler/condition... Indeed. I excluded such things in the interest of brevity, to focus the discussion on my question. :) -- Sahil Tandon sa...@freebsd.org -- http://mail.python.org/mailman/listinfo/python-list
Re: idiomatic analogue of Perl's: while () { ... }
[Thanks to everyone who responded]
Steven D'Aprano wrote:
On Thu, 1 Sep 2011 02:56 pm Sahil Tandon wrote:
%%
# unbuffer STDOUT
sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)
I've never bothered with unbuffered stdout, but that looks fine to me.
I'm not sure if it is necessary though, because print seems to automatically
flush the buffer after each line in my testing. Unless you're printing
repeatedly to the same line, I'm not sure unbuffered stdout is helpful.
I found it necessary because without reopening sys.stdout with buffering
explicitly turned off, I would have to manually flush the buffer after
each print. This is because the program must reply (via writing to
STDOUT) after parsing each line read via STDIN. If I neither disable
buffering nor manually flush after each print, the program just hangs
instead of printing right away.
# process input, line-by-line, and print responses after parsing input
while 1:
rval = parse(raw_input())
if rval == None:
print('foo')
else:
print('bar')
%%
while True is considered slightly more idiomatic (readable), but
otherwise, that seems fine.
Ah, thanks -- I've changed '1' to 'True'.
This works, but while reading the documentation, I thought of using 'for
line in fileinput.input()' in lieu of 'while 1:' construct. This does
not work when debugging the program on the command line -- the script
appears to just hang no matter what is typed into STDIN. I believe this
is because of some internal buffering when using fileinput. Is there a
recommended way to disable such buffering? Am I taking a totally wrong
approach?
I'm not sure anything about fileinput is exactly *recommended*, it's kinda
discouraged on account of being a bit slow. See help(fileinput) at the
interactive prompt.
For what it's worth, the default buffersize for fileinput.input is 0, so if
that doesn't do what you want, I don't think fileinput is the right
solution.
Got it. Based on your and others' response, I will stick with my
existing approach.
--
Sahil Tandon sa...@freebsd.org
--
http://mail.python.org/mailman/listinfo/python-list
idiomatic analogue of Perl's: while () { ... }
I've been tasked with converting some programs from Perl - Python, and
am (as will soon be obvious) new to the language. A few archive/google
searches were inconclusive on a consensus approach, which is OK, but I
just wonder if there is a more Python-esque way to do the following in
Python 2.7.1:
%%
# unbuffer STDOUT
sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)
# process input, line-by-line, and print responses after parsing input
while 1:
rval = parse(raw_input())
if rval == None:
print('foo')
else:
print('bar')
%%
This works, but while reading the documentation, I thought of using 'for
line in fileinput.input()' in lieu of 'while 1:' construct. This does
not work when debugging the program on the command line -- the script
appears to just hang no matter what is typed into STDIN. I believe this
is because of some internal buffering when using fileinput. Is there a
recommended way to disable such buffering? Am I taking a totally wrong
approach?
Feel free to just link me to previous discussions on the topic(s) if I
have missed them. Please be gentle with your cluebats. :-)
Thanks,
--
Sahil Tandon sa...@freebsd.org
--
http://mail.python.org/mailman/listinfo/python-list
