This repo contains various examples for:

• PDM and Poetry-based dependencies management.
• pipx-based installation of poetry and pylint.
• pylint-based linting.
• pytest-based unit tests.
• Command-line arguments parsing.
• Logging.
• Executing Callable objects.
• Type hints.
• Async IO
• Jupyter notebook.
• Dash-based Web application.
• Flask-based API.
• SQLAlchemy-based SQL Database access.
• Interfaces
• TLS-secured gRPC-based microservices.

I built this repo to become a better Python programmer by learning from well-written, lint-checked, unit-tested, " Pythonic" examples, and provide (for myself) an inventory of working examples that I can go back to when I forget how to do something in Python. :-)

The code uses and adapts various examples and tutorials that I found on the Internet from a variety of sites, hence I do not claim any authorship to any of the source code in this repo.

I strive to indicate the examples' sources in the modules' docstring.

There is none.

The code in the repo was written, debugged, and executed using JetBrains' PyCharm 2023.2.5 (Professional Edition).

Python 3.10 or above.

Install it on a Mac with:

brew install python@3.10

PDM and Poetry can share the same pyproject.toml file.

Documentation

brew install pdm

Notes:

• brew also installed python@3.12 as a PDM dependency

pdm init
pdm add jupyter
pdm install

Documentation

brew install pipx
pipx install poetry
pipx ensurepath
# open new terminal
poetry -h

poetry install

poetry run python main.py --example types-hint

poetry run jupyter notebook

Run it with:

pdm run main.py --example type-hints --debug true

Run it with:

pdm run jupyter notebook

• api
• web_app
• web_crawler
• gRPC-based microservices

The above apps use the app_logging module, hence add the Dash's application location to PYTHONPATH before running them, for example:

-> % export PYTHONPATH="${PYTHONPATH}:/Users/bertrandrigaldies/Projects/python-by-example"

The gRPC examples were the results of doing a code-along of this tutorial

To generate the protobuf bindings, and run the client and recommendations server by hand (outside of Docker):

For the server:

cd apps/grpc/recommendations
python -m grpc_tools.protoc -I ../protobufs --python_out=. \
         --grpc_python_out=. ../protobufs/recommendations.proto

For the Web server:

cd apps/grpc/marketplace
python -m grpc_tools.protoc -I ../protobufs --python_out=. \
         --grpc_python_out=. ../protobufs/recommendations.proto

When running in Docker, the protobuf bindings are generated as part of the Docker image builds for both the client and recommendations server. See the next section for the instructions on how to run the demo in Docker with docker-compose.

Build the Docker images for the client and recommendations server as shown below (see also the second comment line at the top of the Docker files):

1. Build the client's CA and TLS public key

openssl req -x509 -nodes -newkey rsa:4096 -keyout ca.key -out ca.pem -subj /O=me

2. Build the client's Docker image

DOCKER_BUILDKIT=1 docker build . -f marketplace/Dockerfile -t marketplace --secret id=ca.key,src=ca.key

3. Build the recommendations server's Docker image

DOCKER_BUILDKIT=1 docker build . -f recommendations/Dockerfile -t recommendations --secret id=ca.key,src=ca.key

Run the dockerized demo with docker-compose as shown below:

docker-compose up

Shut down the application as shown below from the terminal where the demo was started (see above):

1. Ctrl-C
2. docker-compose down

See setup_logging() in app_logging.py.

See parser.parse_args() in main.py.

See register_examples() in ./examples/registry/registry.py for the use if the Callable generic.

See run_examples() in ./examples/typehints/type_hints_example.py.

poetry add aiofiles
poetry add aiohttp

poetry run python main.py --example async-io --debug true -p 3 -c 2 
poetry run python main.py --example generators --debug true

poetry install pytest

poetry run python -m pytest

pipx install pylint

pylint **/*.py 

poetry add mypy

mypy **/*.py

In order to address mypy errors such as:

error: Library stubs not installed for "pandas"  [import-untyped]

Install the supporting type stubs:

poetry add pandas-stubs
poetry add types-aiofiles
poetry add types-requests

poetry add flask

poetry run flask --app ./apps/api/resp_api --debug run

• View incomes
• Add income: Run the Python post_income.py program as shown below:

poetry run python ./apps/api/post_income.py 

The example uses the Dash framework, and tutorial.

poetry install dash

poetry run python ./apps/web_app/app_with_bootstrap_styling.py

poetry install sqlalchemy

poetry add redis

cd ./examples/cache
docker compose up

Pre-requisite: Install the Redis client

brew install redis

redis-cli -h localhost -p 6379

poetry install tqdm

poetry install progressbar2

poetry add numpy