Creating a custom magic command in an IPython extension

IPython comes with a rich set of magic commands. You can get the complete list with the %lsmagic command. IPython also allows you to create your own magic commands. In this section, we will create a new cell magic that compiles and executes C++ code in the Notebook.

We first import the register_cell_magic function:

In [1]: from IPython.core.magic import register_cell_magic

To create a new cell magic, we create a function that takes a line (containing possible options) and a cell's contents as its arguments, and we decorate it with @register_cell_magic, as shown here:

In [2]: @register_cell_magic
        def cpp(line, cell):
            """Compile, execute C++ code, and return the
            standard output."""
            # We first retrieve the current IPython interpreter
            # instance.
            ip = get_ipython()

            # We define the source and executable filenames.
            source_filename = '_temp.cpp'
  ...