sphinx-icontract 2.0.0

Implications

Sphinx-icontract tries to infer the implications from the conditions and render them as implication (... ⇒ ...). We implemented a rule-based matching that covers most of the practical use cases:

• not A or B is translated to A ⇒ B.

• Expressions are negated, so x < y or B is translated to x >= y ⇒ B. More general expressions are negated with not: from x.y() or B to not x.y() ⇒ B.

• If-Expressions are translated from B if A else True to A ⇒ B.

We found implications in form of if-expressions to be confusing when read in source code and encourage programmers to use disjunction form instead.

Custom Errors

If you specify custom errors in the contract, sphinx-icontract will try to include the error in the documentation.

The error type will be inferred from the contract’s error argument. If the error message is given as a string literal and there is no contract description, the error message will be used to describe the contract so that you do not have to specify the description twice (once in the description of the contract and once in the error message).

For example:

@icontract.pre(lambda x: x > 0, error=lambda: ValueError("x positive"))
def some_func(x: int) -> None:
    pass

will be documented as:

:requires:
                        * :code:`x > 0` (x positive; raise :py:class:`ValueError`)

If both the description and the error message are given, only the description will be included:

@icontract.pre(lambda x: x > 0, description="x must be positive", error=lambda: ValueError("x positive"))
def some_func(x: int) -> None:
    pass

will be rendered as:

:requires:
    * :code:`x > 0` (x must be positive; raise :py:class:`ValueError`)

Pre-commit Checks

We provide a set of pre-commit checks that lint and check code for formatting.

Namely, we use:

• yapf to check the formatting.

• The style of the docstrings is checked with pydocstyle.

• Static type analysis is performed with mypy.

• Various linter checks are done with pylint.

• Contracts are linted with pyicontract-lint.

• Doctests are executed using the Python doctest module.

Run the pre-commit checks locally from an activated virtual environment with development dependencies:

./precommit.py

• The pre-commit script can also automatically format the code:

./precommit.py  --overwrite