Greeter
=======
Check out this tutorial on GitHub: `greeter <https://github.com/justmert/arbitrum-python-tutorials/tree/master/tutorials/greeter>`__


``greeter`` is a simple demo of Arbitrum’s Parent-to-child message
passing system (aka “L1-to-L2” or “retryable tickets”).

It deploys 2 contracts - one to the parent chain, and another to the
child chain, and has the parent chain contract send a message to the
child chain contract to be executed automatically.

The script and contracts demonstrate how to interact with Arbitrum’s
core bridge contracts to create these retryable messages, how to
calculate and forward appropriate fees from parent to child, and how to
use Arbitrum’s Parent-to-child message `address
aliasing <https://docs.arbitrum.io/how-arbitrum-works/l1-to-l2-messaging#address-aliasing>`__.

See `exec.py  <https://github.com/justmert/arbitrum-python-tutorials/tree/master/tutorials/greeter/scripts/exec.py>`__ for inline explanation.

`Click
here <https://docs.arbitrum.io/how-arbitrum-works/l1-to-l2-messaging>`__
for more info on retryable tickets.

Set environment variables
-------------------------

Set the values shown in ``.env-sample`` as environmental variables. To
copy it into a ``.env`` file:

.. code:: bash

   cp .env-sample .env

You’ll still need to edit some variables, i.e., ``PRIVATE_KEY``,
``CHAIN_RPC`` and ``PARENT_CHAIN_RPC``.

Note that you can also set the environment variables in an ``.env`` file
in the root of the monorepo, which will be available in all tutorials.

Run
---

Install dependencies and build the contracts:

::

   chmod +x ./build.sh && ./build.sh

Run the script:

::

   python3 scripts/exec.py

.. raw:: html

   <p align="left">

.. raw:: html

   </p>