reiter 0.5.0

Wrapper for Python iterators and iterables that implements a list-like random-access interface.

Wrapper for Python iterators and iterables that implements a list-like random-access interface by caching retrieved items for later reuse.

Package Installation and Usage

The package is available on PyPI:

python -m pip install reiter

The library can be imported in the usual way:

import reiter
from reiter import reiter

Examples

The library makes it possible to wrap iterators and iterables within an interface that enables repeated iteration over – and random access by index of – the items contained within. A reiter instance yields the same sequence of items as the wrapped iterator:

>>> from reiter import reiter
>>> xs = iter([1, 2, 3])
>>> ys = reiter(xs)
>>> list(ys)
[1, 2, 3]

However, unlike an iterator, the instance of this class can be iterated any number of times:

>>> list(ys), list(ys)
([1, 2, 3], [1, 2, 3])

Furthermore, it is also possible to access elements by their index:

>>> xs = iter([1, 2, 3])
>>> ys = reiter(xs)
>>> ys[0], ys[1], ys[2]
(1, 2, 3)

The built-in Python next function is also supported, and any attempt to retrieve an item once the sequence of items is exhausted raises an exception in the usual manner:

>>> xs = reiter(iter([1, 2, 3]))
>>> next(xs), next(xs), next(xs)
(1, 2, 3)
>>> next(xs)
Traceback (most recent call last):
  ...
StopIteration

However, all items yielded during iteration can be accessed by their index, and it is also possible to iterate over those items again:

>>> xs[0], xs[1], xs[2]
(1, 2, 3)
>>> [x for x in xs]
[1, 2, 3]

Instances of reiter support additional methods, as well. For example, the has method returns a boolean value indicating whether a next item is available and the length method returns the length of the sequence of items emitted by the instance (once no more items can be emitted):

>>> xs = reiter(iter([1, 2, 3]))
>>> xs.has(), xs.has(), xs.has(), xs.has()
(True, True, True, False)
>>> xs.length()
3

Documentation

The documentation can be generated automatically from the source files using Sphinx:

cd docs
python -m pip install -r requirements.txt
sphinx-apidoc -f -E --templatedir=_templates -o _source .. ../setup.py && make html

Testing and Conventions

All unit tests are executed and their coverage is measured when using pytest (see setup.cfg for configuration details):

python -m pip install pytest pytest-cov
python -m pytest

All unit tests are included in the module itself and can be executed using doctest:

python reiter/reiter.py -v

Style conventions are enforced using Pylint:

python -m pip install pylint
python -m pylint reiter

Contributions

In order to contribute to the source code, open an issue or submit a pull request on the GitHub page for this library.

Versioning

The version number format for this library and the changes to the library associated with version number increments conform with Semantic Versioning 2.0.0.

Publishing

This library can be published as a package on PyPI by a package maintainer. Install the wheel package, remove any old build/distribution files, and package the source into a distribution archive:

python -m pip install wheel
rm -rf dist *.egg-info
python setup.py sdist bdist_wheel

Next, install the twine package and upload the package distribution archive to PyPI:

python -m pip install twine
python -m twine upload dist/*