Subprocess with a Python Session?

[Calvin Spealman]

No matter what I do I cant get the following code to do what I expect.
I hadn't used subprocess t o read and write to pipes of a
still-running app, and I just can't seem to get it right. What gives?

import subprocess

p = subprocess.Popen("python", stdout=subprocess.PIPE, stdin=subprocess.PIPE)
p.stdin.write('print 10\n')
assert p.stdout.readline() == '10\n'

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[Nick Craig-Wood]

Calvin Spealman <ir********@gmail.comwrote:

No matter what I do I cant get the following code to do what I expect.
I hadn't used subprocess t o read and write to pipes of a
still-running app, and I just can't seem to get it right. What gives?

import subprocess

p = subprocess.Popen("python", stdout=subprocess.PIPE, stdin=subprocess.PIPE)
p.stdin.write('print 10\n')
assert p.stdout.readline() == '10\n'

To read and write to a still running app, you'll want to use pexpect
probably.

http://pexpect.sourceforge.net/

>>import pexpect
p = pexpect.spawn("python")
p.expect(">>>")

0

>>p.sendline("print 10\n")

10

>>p.readline()

' print 10\r\n'

>>p.readline()

'10\r\n'

>>>

Note that running python under pexpect puts it into interactive
mode.

--
Nick Craig-Wood <ni**@craig-wood.com-- http://www.craig-wood.com/nick