Preparation

Before coming to the tutorial, please do the following:

1. Have Python 3.7 installed in your laptop. Note: It’s important that you’re running Python 3.7 (or above) because we will use some of the new features added in 3.7 in this tutorial.

   • Here’s a tutorial that will help you get set up.

2. Install the dependencies, preferably in a virtual environment. For this tutorial, we’ll use venv.

Create a new virtual environment using venv:

python3.7 -m venv .venv

Activate the virtual environment. On Unix, Mac OS:

source .venv/bin/activate

On Windows:

.venv\Scripts\activate.bat

Install the dependencies, listed in the requirements.txt file. You can download the file, or clone this repository:

(.venv) python -m pip install -U pip -r requirements.txt

3. Verify that you correctly have Python 3.7 installed. If you’re able to run the following code, then you’re good to go.

import asyncio


async def main() -> None:
    print("Hello ...")
    await asyncio.sleep(1)
    print("... World!")


# Python 3.7+
asyncio.run(main())

Resources and documentation links

Tools and documentations that we’ll use throughout this tutorial.

venv

Python venv tutorial documentation.

aiohttp

• Installation: python3.7 -m pip install aiohttp.

• aiohttp documentation

• aiohttp source code

• Owner: Andrew Svetlov

f-strings

We will use some f-strings during this tutorial.

My talk about f-strings.

Example:

first_name = "bart"
last_name = "simpson"

# old style %-formatting
print("Hello %s %s" % (first_name, last_name))

# str.format
print("Hello {first_name} {last_name}".format(first_name=first_name, last_name=last_name))

# f-string
print(f"Hello {first_name} {last_name}")

asyncio

aiohttp is async Python library. Read up the quick intro to asyncio.

type annotations

Our code examples use type annotations and checked with mypy. It is optional.

• typing documentation: https://docs.python.org/3/library/typing.html

• mypy documentation: https://mypy.readthedocs.io/en/stable/

dataclass

The dataclass module provides a decorator and functions for automatically adding generated special methods such as __init__() and __repr__() to user-defined classes. It was originally described in PEP 557.

Example:

@dataclass
class InventoryItem:
    '''Class for keeping track of an item in inventory.'''
    name: str
    unit_price: float
    quantity_on_hand: int = 0

    def total_cost(self) -> float:
        return self.unit_price * self.quantity_on_hand

dataclass documentation.

aiohttp-jinja2

jinja2 template renderer for aiohttp.web.

aiohttp-jinja2 documentation.

aiohttp-session

https://aiohttp-session.readthedocs.io/en/stable/

click

Click is a Python package for creating beautiful command line interfaces in a composable way with as little code as necessary. It’s the “Command Line Interface Creation Kit”.

click documentation.