Multiple prompts when starting inferior Python

[Joost Kremers <joost.m.kremers@gmail.com>]

Hi,

Whenever I start an interactive Python session in Emacs, I get four
empty prompts instead of one. That is, when I do `M-x run-python' (or
start from a Python file with `C-c C-z'), the *Python* buffer looks like
this:

,----
| Python 2.7.3 (default, Feb 27 2014, 19:58:35) 
| Type "copyright", "credits" or "license" for more information.
| 
| IPython 0.12.1 -- An enhanced Interactive Python.
| ?         -> Introduction and overview of IPython's features.
| %quickref -> Quick reference.
| help      -> Python's own help system.
| object?   -> Details about 'object', use 'object??' for extra details.
| 
| In [1]: 
| In [2]: 
| In [3]: 
| In [4]: 
| 
`----

I use elpy and IPython, but that doesn't make a difference. This is what
I get when running an interactive Python shell with `emacs -Q':

,----
| Python 2.7.3 (default, Feb 27 2014, 19:58:35) 
| [GCC 4.6.3] on linux2
| Type "help", "copyright", "credits" or "license" for more information.
| >>> >>> >>> >>> 
`----

Note the four `>>>'.

This is something that's been happening a while, and it's never really
bothered me. However, the other day someone on Reddit asked the same
question,[1] which prompted me to do some digging. I ran `run-python'
though the debugger and it seems that those prompts are caused by the
function `python-shell-send-setup-code', which sends the contents of the
variables listed in the variable `python-shell-setup-codes' to the
inferior python process when it's started. The default value of this
option is:

,----
| (python-shell-completion-setup-code python-ffap-setup-code python-eldoc-setup-code)
`----

Each of these variables contains some code which, when sent to the
inferior python process, results in a new prompt being displayed, even
though the actual command is not shown.

Is this something that should be considered a bug? Can it be avoided
somehow or should I simply live with it? (Which isn't very difficult, it
doesn't seem to affect anything.)

TIA


[1] http://www.reddit.com/r/emacs/comments/24fy1q/help_get_rid_of_multiple_inputs_when_running_a/


-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)