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Version: 2.22

repl

Open a REPL for interactive development.

Pants will load a REPL with all of your specified source code and any of its third-party dependencies, which allows you to import those values.

IPython​

In addition to the default Python shell, Pants supports the improved IPython shell.

To use IPython, run pants repl --shell=ipython. To permanently use IPython, add this to your pants.toml:

pants.toml
[repl]
shell = "ipython"

You can change IPython's version like any other tool, using install_from_resolve.

If you use a version lower than IPython 7, then you must set [ipython].ignore_cwd = false to avoid Pants setting an option that did not exist in earlier IPython releases.

Python 2 support

Pants uses IPython 7 by default, which does not work with Python 2. You can use install_from_resolve to install IPython 5:

[python.resolves]
...
ipython = "3rdparty/python/ipython.lock"

[ipython]
install_from_resolve = "ipython"
ignore_cwd = false

Examples​

Shell
$ pants repl helloworld/greet/greeting.py

Python 3.7.6 (default, Feb 26 2020, 08:28:08)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from helloworld.greet.greeting import Greeter
>>> Greeter().greet("Pants")
'buenas tardes, Pants!'
>>> from translate import Translator
>>> Translator(to_lang="fr").translate("Good morning.")
'Salut.'

This will not load any of your code:

Shell
❯ pants repl --shell=ipython
Python 3.9.12 (main, Mar 26 2022, 15:45:34)
Type 'copyright', 'credits' or 'license' for more information
IPython 7.34.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: 21 * 4
Out[1]: 84

pants repl :: will load all your code.

To pass arguments to the repl program, use -- at the end of the command, like this:

Shell
$ pants repl --shell=ipython -- -i helloworld/main.py

Check the documentation for the --repl-args option in pants help repl to see which shells support passing arguments.

Tip: how to exit the REPL

Either type exit() and hit enter, or press ctrl+d.