On 05/10/2017 07:57, Gregory Ewing wrote:
Steve D'Aprano wrote:
I recall that the Pascal compiler had to do some clever behind the scenes
jiggery-pokery to get eof() to work, but that's what compilers are
supposed
to do: make common tasks easy for the programmer.
Sometimes the jiggery-pokery worked, sometimes it didn't.
For example, the following wouldn't work as expected:
while not eof(input) do begin
write(output, 'Enter something:');
readln(input, buffer);
process(buffer);
end
because the eof() would block waiting for you to enter
something, so the prompt wouldn't get printed at the
right time.
Basically, Pascal's eof-flag model was designed for
batch processing, and didn't work very well for
interactive use.
This doesn't make sense. For interactive use, you wouldn't bother
testing for eof, as you'd be testing the eof status of the keyboard.
You might want a way of the user indicating end-of-data, but that's
different; you don't want to abruptly send an EOF (via Ctrl-C, D, Z,
Break or whatever). That would be a crass way of doing it. Besides you
might want to continue interacting with the next part of the program.
So the loop would be like this (Python 3; don't know why it doesn't work
in Python 2):
while 1:
buffer = input("Enter something (Type quit to finish): ")
if buffer == "quit": break
print ("You typed:", buffer) # process(buffer)
print ("Bye")
This is a loop-and-a-half.
--
bartc
--
https://mail.python.org/mailman/listinfo/python-list
