If you have recently upgraded your Mac OS to Sierra and found that the arrow keys no longer work in the Python shell, you are not alone. This issue is a common problem faced by many Python developers after upgrading their operating system. However, there are several ways to solve this problem and restore the functionality of the arrow keys in the Python shell.
Solution 1: Install readline module
One of the easiest ways to fix this issue is by installing the readline module. The readline module provides a set of functions for editing command lines as they are typed in. To install the readline module, open your terminal and run the following command:
pip install readline
After installing the readline module, restart your Python shell and the arrow keys should start working again.
Solution 2: Use rlwrap
If installing the readline module does not solve the problem, you can try using rlwrap. Rlwrap is a wrapper that provides readline-like functionality for any command-line application. To install rlwrap, open your terminal and run the following command:
brew install rlwrap
Once rlwrap is installed, you can use it to launch the Python shell by running the following command:
This will launch the Python shell with readline-like functionality, allowing you to use the arrow keys.
Solution 3: Use IPython
If the above solutions do not work for you, another option is to use IPython instead of the default Python shell. IPython is an enhanced interactive Python shell that provides many additional features, including support for the arrow keys. To install IPython, open your terminal and run the following command:
pip install ipython
After installing IPython, you can launch it by running the following command:
IPython will provide a more interactive and feature-rich Python shell experience, including support for the arrow keys.
Out of the three options, using IPython is generally considered the best solution. IPython not only solves the arrow key issue but also provides a more powerful and user-friendly Python shell experience. It offers features like tab completion, syntax highlighting, and history navigation, making it a preferred choice for many Python developers.