Define sys.ps{1,2}

[fperez]

See https://bugs.launchpad.net/ipython/+bug/512826 for prior history.

Summary: we should define sys.ps{1,2} to make it easier for scripts to detect if they are being loaded interactively or not, and without ipython-specific checks.

[bfroehle]

I'm not sure that setting sys.ps1 will make it easier for scripts to detect if they are being loaded interactively. For example, consider

$ cat tst.py
import sys
try: print "sys.ps1=%r" % sys.ps1
except: print "no sys.ps1"

$ python -i tst.py
no sys.ps1
>>>

I think the author of the original issue might be better off passing some command line flags and parsing sys.argv.

Nonetheless it is true that execfile('tst.py') behaves differently

$ python
...
>>> execfile('tst.py')
sys.ps1='>>> '

and it'd be easy to set sys.ps1 in InteractiveShell.init_prompts or similar.

[fperez]

Did you mean to open a PR for this?

[bfroehle]

Well, I'm not sure how I feel about it, so I haven't yet... but I will now, just to get some other commentary on the issue.