Provide design-by-contract with informative violation messages.

Navigation

Verified details

These details have been verified by PyPI
Maintainers
Avatar for mristin from gravatar.com mristin Avatar for Sasha93 from gravatar.com Sasha93

Unverified details

These details have not been verified by PyPI
Project links
Meta
  • License: MIT License (License :: OSI Approved :: MIT License)
  • Author: Marko Ristin
  • Tags design-by-contract, precondition, postcondition, validation
Classifiers

Project description

icontract

Continuous integration https://coveralls.io/repos/github/Parquery/icontract/badge.svg?branch=master PyPI - version PyPI - Python Version Documentation Gitter chat

icontract provides design-by-contract to Python3 with informative violation messages and inheritance.

It also gives a base for a flourishing of a wider ecosystem:

Teasers

We give a couple of teasers here to motivate the library. Please see the documentation available on icontract.readthedocs.io for a full scope of its capabilities.

The script is also available as a repl.it post.

>>> import icontract

>>> @icontract.require(lambda x: x > 3)
... def some_func(x: int, y: int = 5) -> None:
...     pass
...

>>> some_func(x=5)

# Pre-condition violation
>>> some_func(x=1)
Traceback (most recent call last):
  ...
icontract.errors.ViolationError: File <doctest README.rst[1]>, line 1 in <module>:
x > 3: x was 1

# Pre-condition violation with a description
>>> @icontract.require(lambda x: x > 3, "x must not be small")
... def some_func(x: int, y: int = 5) -> None:
...     pass
...
>>> some_func(x=1)
Traceback (most recent call last):
  ...
icontract.errors.ViolationError: File <doctest README.rst[4]>, line 1 in <module>:
x must not be small: x > 3: x was 1

# Pre-condition violation with more complex values
>>> class B:
...     def __init__(self) -> None:
...         self.x = 7
...
...     def y(self) -> int:
...         return 2
...
...     def __repr__(self) -> str:
...         return "instance of B"
...
>>> class A:
...     def __init__(self) -> None:
...         self.b = B()
...
...     def __repr__(self) -> str:
...         return "instance of A"
...
>>> SOME_GLOBAL_VAR = 13
>>> @icontract.require(lambda a: a.b.x + a.b.y() > SOME_GLOBAL_VAR)
... def some_func(a: A) -> None:
...     pass
...
>>> an_a = A()
>>> some_func(an_a)
Traceback (most recent call last):
  ...
icontract.errors.ViolationError: File <doctest README.rst[9]>, line 1 in <module>:
a.b.x + a.b.y() > SOME_GLOBAL_VAR:
SOME_GLOBAL_VAR was 13
a was instance of A
a.b was instance of B
a.b.x was 7
a.b.y() was 2

# Post-condition
>>> @icontract.ensure(lambda result, x: result > x)
... def some_func(x: int, y: int = 5) -> int:
...     return x - y
...
>>> some_func(x=10)
Traceback (most recent call last):
  ...
icontract.errors.ViolationError: File <doctest README.rst[12]>, line 1 in <module>:
result > x:
result was 5
x was 10


# Pre-conditions fail before post-conditions.
>>> @icontract.ensure(lambda result, x: result > x)
... @icontract.require(lambda x: x > 3, "x must not be small")
... def some_func(x: int, y: int = 5) -> int:
...    return x - y
...
>>> some_func(x=3)
Traceback (most recent call last):
  ...
icontract.errors.ViolationError: File <doctest README.rst[14]>, line 2 in <module>:
x must not be small: x > 3: x was 3

# Invariant
>>> @icontract.invariant(lambda self: self.x > 0)
... class SomeClass:
...     def __init__(self) -> None:
...         self.x = -1
...
...     def __repr__(self) -> str:
...         return "some instance"
...
>>> some_instance = SomeClass()
Traceback (most recent call last):
 ...
icontract.errors.ViolationError: File <doctest README.rst[16]>, line 1 in <module>:
self.x > 0:
self was some instance
self.x was -1

Installation

  • Install icontract with pip:

pip3 install icontract

Versioning

We follow Semantic Versioning. The version X.Y.Z indicates:

  • X is the major version (backward-incompatible),

  • Y is the minor version (backward-compatible), and

  • Z is the patch version (backward-compatible bug fix).

Project details

Verified details

These details have been verified by PyPI
Maintainers
Avatar for mristin from gravatar.com mristin Avatar for Sasha93 from gravatar.com Sasha93

Unverified details

These details have not been verified by PyPI
Project links
Meta
  • License: MIT License (License :: OSI Approved :: MIT License)
  • Author: Marko Ristin
  • Tags design-by-contract, precondition, postcondition, validation
Classifiers

Release history Release notifications | RSS feed

2.7.1

2.7.0

2.6.6

2.6.5

2.6.4

2.6.3

2.6.2

2.6.1

2.6.0

2.5.5

2.5.4

2.5.3

This version

2.5.2

2.5.1

2.5.0

2.4.1

2.4.0

2.3.7

2.3.6

2.3.5

2.3.4

2.3.3.post1

2.3.2

2.3.1

2.3.0

2.2.0

2.1.0

2.0.7

2.0.6

2.0.5

2.0.4

2.0.3

2.0.2

2.0.1

2.0.0

1.7.2

1.7.1

1.7.0

1.6.1

1.6.0

1.5.9

1.5.8

1.5.7

1.5.6

1.5.5

1.5.4

1.5.3

1.5.2

1.5.1

1.5.0

1.4.1

1.4.0

1.3.0

1.2.3

1.2.2

1.2.1

1.2.0

1.1.0

1.0.3

1.0.2

1.0.1

1.0.0

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

icontract-2.5.2.tar.gz (42.0 kB view details)

Uploaded Source

File details

Details for the file icontract-2.5.2.tar.gz.

File metadata

  • Download URL: icontract-2.5.2.tar.gz
  • Upload date:
  • Size: 42.0 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? No
  • Uploaded via: twine/3.4.1 importlib_metadata/4.3.1 pkginfo/1.7.0 requests/2.25.1 requests-toolbelt/0.9.1 tqdm/4.61.0 CPython/3.9.5

File hashes

Hashes for icontract-2.5.2.tar.gz
Algorithm Hash digest
SHA256 34c347c449c62a636c2960f7d2481a70764aae9a005b0c68fe3b98de025acced
MD5 e1fb682db2a7cd5d2cf16a8e51220268
BLAKE2b-256 cd0cd37cc1738a2be945d7260af719e55baae6d278b3677490b9515255e3e068

See more details on using hashes here.

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page