When I upgraded to Leopard, I noticed some craziness with IPython. It was very hard to verbalize and nearly impossible to Google. Luckily I use SSH, Gnu screen, and VIM all day everyday and have a lot of experience with terminal emulation issues. One of the big culprets there is "readline". I was able to find discussions about Leopard Ipython and readline, but not the weirdness I was trying to solve.

So, why the ShowMeDo? "Googlability". I'll describe the problem verbally so that others can take comfort in knowing they are not alone.

After installing Mac OS X Leopard, I ran into trouble with IPython acting crazy! I noticed when launching IPython that it said Leopard libedit was detected. (It turns out that this is a crucial detail.) IPython seemed to work fine at first. I had tab completion and such, but when defining functions on the fly, I had to indent my code manually with spaces. The real weirdness occurred when trying to use the up arrow to navigate through the command history. When a multi-line history entry (like a method/function definition, for loop, or if block) was encountered, the left alignment went all wrong. Things would continue to get worse with every key stroke. All you can say is "Worse Than Failure."

There are a lot of discussions about Leopard, Python, and readline that will turn up on Google, but most deal with the versions of IPython that where out before the Leopard launch. The "readline.parse_and_bind" thing seems to be resolved/patched in the latest versions. But in order to solve the problem discribed above, you need ipython to find readline. I'm going to suggest that we should all be using pip at this point so I'm updating these instructions to:

sudo pip uninstall ipython;

sudo pip install readline pyreadline ipython;

My original suggestion was to install the readline EGG like so:

sudo easy_install -f http://ipython.scipy.org/dist/ readline

as described here: http://ipython.scipy.org/moin/InstallationOSXLeopard HOWEVER, the python commu