We can define an alias in ipython with the %alias magic function, like this:
>>> d
NameError: name 'd' is not defined
>>> %alias d date
>>> d
Fri May 15 00:12:20 AEST 2015
This escapes to the shell command date when you type d into ipython.
But I want to define an alias to execute some python code, in the current interpreter scope, rather than a shell command. Is that possible? How can we make this kind of alias?
I work in the interactive interpreter a lot, and this could save me a lot of commands I find myself repeating often, and also prevent some common typos.
The normal way to do this would be to simply write a python function, with a def. But if you want to alias a statement, rather than a function call, then it's actually a bit tricky.
You can achieve this by writing a custom magic function. Here is an example, which effectively aliases the import statement to get, within the REPL.
from IPython.core.magic import register_line_magic
@register_line_magic
def get(line):
code = f"import {line}"
print("-->", code)
exec(code, globals())
del get # in interactive mode-remove from scope so function doesn't shadow magic
edit: below is the previous code, for older versions of IPython
from IPython.core.magic_arguments import argument, magic_arguments
@magic_arguments()
@argument('module')
def magic_import(self, arg):
code = 'import {}'.format(arg)
print('--> {}'.format(code))
self.shell.run_code(code)
ip = get_ipython()
ip.define_magic('get', magic_import)
Now it is possible to execute get statements which are aliased to import statements.
Demo:
In [1]: get json
--> import json
In [2]: json.loads
Out[2]: <function json.loads>
In [3]: get potato
--> import potato
---------------------------------------------------------------------------
ImportError Traceback (most recent call last)
<string> in <module>()
ImportError: No module named potato
In [4]:
Of course, this is extendible to arbitrary python code, and optional arguments are supported aswell.