Hello,
I'm trying to use pexpect to grab interactions with Python's REPL. I am having
trouble with tracebacks. Possibly it is related to buffering (hence the
subject line) but I admit that's a guess.
At the end of this message is a minimal example program. It feeds three
commands to a python interpreter. The second command should fail like this.
>>> a
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'a' is not defined
>>>
However, pexpect only returns part of that "Traceback .." message, that is,
pexpect is not waiting for the >>> prompt. I have included the output of the
program below, after the program.
(In case it helps, spawning Python with -u doesn't make any difference.)
I'd be very glad for any suggestions.
Jim
The program:
--------------------------------------------------
#!/usr/bin/python
import sys, os, re, pprint
import pexpect
cmds = ['1+2', 'a', '3+4']
PROMPT = '>>> '
PROMPT_CONTINUE = '... '
child = pexpect.spawn('python') # start the repl
# child = pexpect.spawn('python', maxread=1) # makes no difference
child.expect([PROMPT])
print " initial child.before=",pprint.pformat(child.before)
print " initial child.after=",pprint.pformat(child.after)
r = []
for cmd in cmds:
print "++++++ cmd=",pprint.pformat(cmd)
child.sendline(cmd)
dex = child.expect([PROMPT, PROMPT_CONTINUE])
print " child.before=",pprint.pformat(child.before)
print " child.after=",pprint.pformat(child.after)
r.append(child.before)
print "r=",pprint.pformat(r)
-----------------------------------------
My screen when I run this (Ubuntu 12.04 with Python 2.7.3).
$ ./minex.py
initial child.before= 'Python 2.7.3 (default, Aug 1 2012, 05:16:07) \r\n[GCC
4.6.3] on linux2\r\nType "help", "copyright", "credits" or "license" for more
information.\r\n'
initial child.after= '>>> '
++++++ cmd= '1+2'
child.before= '1+2\r\n3\r\n'
child.after= '>>> '
++++++ cmd= 'a'
child.before= 'a\r\nTraceb'
child.after= 'ack '
++++++ cmd= '3+4'
child.before= '(m'
child.after= 'ost '
r= ['1+2\r\n3\r\n', 'a\r\nTraceb', '(m']
--
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