memoir

In what follows

• python is an alias for python3.5 or any later version (python3.6 and so on),
• pypy is an alias for pypy3.5 or any later version (pypy3.6 and so on).

Installation

Install the latest pip & setuptools packages versions:

• with CPython

  python -m pip install --upgrade pip setuptools
  

• with PyPy

  pypy -m pip install --upgrade pip setuptools
  

User

Download and install the latest stable version from PyPI repository:

• with CPython

  python -m pip install --upgrade memoir
  

• with PyPy

  pypy -m pip install --upgrade memoir
  

Developer

Download the latest version from GitHub repository

git clone https://github.com/lycantropos/memoir.git
cd memoir

Install:

• with CPython

  python setup.py install
  

• with PyPy

  pypy setup.py install
  

Usage

Let's suppose we are defining a class with expensive read-only property which can be calculated once and reused afterwards.

Common way of solving this is by introducing private'ish attribute like

>>> class Example:
...     @property
...     def expensive_property(self):
...         try:
...             result = self._expensive_property
...         except AttributeError:
...             result = do_expensive_calculations(...)
...             self._expensive_property = result
...         return result

this works fine, but each such property

• introduces an extra attribute,
• requires a lot of boilerplate code.

If we have

• weakly-referencable (which is by default if not suppressed explicitly, e.g. by using __slots__ class variable),
• hashable

class we can implement it like

>>> from memoir import cached
>>> class Example:
...     @cached.property_
...     def expensive_property(self):
...         return do_expensive_calculations(...)

Development

Bumping version

Preparation

Install bump2version.

Pre-release

Choose which version number category to bump following semver specification.

Test bumping version

bump2version --dry-run --verbose $CATEGORY

where $CATEGORY is the target version number category name, possible values are patch/minor/major.

Bump version

bump2version --verbose $CATEGORY

This will set version to major.minor.patch-alpha.

Release

Test bumping version

bump2version --dry-run --verbose --tag release

Bump version

bump2version --verbose --tag release

This will set version to major.minor.patch and add Git tag.

Notes

To avoid inconsistency between branches and pull requests, bumping version should be merged into master branch as separate pull request.

Running tests

Plain:

• with CPython

  python setup.py test
  

• with PyPy

  pypy setup.py test
  

Inside Docker container:

• with CPython

  docker-compose --file docker-compose.cpython.yml up
  

• with PyPy

  docker-compose --file docker-compose.pypy.yml up
  

Bash script (e.g. can be used in Git hooks):

• with CPython

  ./run-tests.sh
  

  or

  ./run-tests.sh cpython
  

• with PyPy

  ./run-tests.sh pypy
  

PowerShell script (e.g. can be used in Git hooks):

• with CPython

  .\run-tests.ps1
  

  or

  .\run-tests.ps1 cpython
  

• with PyPy

  .\run-tests.ps1 pypy