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Overview

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A magic shortcut to generate __repr__ methods for your classes.

  • Free software: BSD license

Installation

pip install repr

This package contains a single module magic_repr called so to not conflict with standart python’s repr.

Reasoning

What do you think each time, writing such code?

def __repr__(self):
    return """
Issue(changelog={self.changelog},
      type={self.type},
      comment={self.comment},
      created_at={self.created_at},
      resolved_at={self.resolved_at})""".format(self=self).strip().encode('utf-8')

Isn’t this much better and readable?

__repr__ = make_repr('changelog', 'type', 'comment', 'created_at', 'resolved_at')

And this produces much nicer output:

<Issue changelog=<Changelog namespace=u'python'
                            name=u'geocoder'
                            source=u'https://github.com/DenisCarriere/geocoder'>
       type=u'wrong-version-content'
       comment=u'AllMyChanges should take release notes from the web site.'
       created_at=datetime.datetime(2016, 6, 17, 6, 44, 52, 16760, tzinfo=<UTC>)
       resolved_at=None>

Another advantage of the magic_repr

Is it’s recursiveness. If you use magic_repr for your objects and they include each other, then representation of the parent object will include child objects properly nested:

<Foo bars={1: <Bar first=1
                   second=2
                   third=3>,
           2: <Bar first=1
                   second=2
                   third=3>,
           u'три': <Bar first=1
                        second=2
                        third=3>}>

And all this for free! Just do __repr__ = make_repr().

Usage

For simple cases it is enough to call make_repr without arguments. It will figure out which attributes object has and will output them sorted alphabetically.

You can also specify which attributes you want to include in “representaion”:

__repr__ = make_repr('foo', 'bar')

And to specify a function to create a value for an attribute, using keywords:

class Some(object):
    def is_active(self):
        return True

Some.__repr__ = make_repr(active=Some.is_active)

Pay attention, that in this case __repr__ was created after the class definition. This is because inside of the class it can’t reference itself.

Development

To run the all tests run:

tox

Note, to combine the coverage data from all the tox environments run:

Windows 
set PYTEST_ADDOPTS=--cov-append
tox
Other 
PYTEST_ADDOPTS=--cov-append tox

Reference

magic_repr

magic_repr.make_repr(*args, **kwargs)[source]

Returns __repr__ method which returns ASCII representaion of the object with given fields.

Without arguments, make_repr generates a method which outputs all object’s non-protected (non-undercored) arguments which are not callables.

Accepts *args, which should be a names of object’s attributes to be included in the output:

__repr__ = make_repr('foo', 'bar')

If you want to generate attribute’s content on the fly, then you should use keyword arguments and pass a callable of one argument:

__repr__ = make_repr(foo=lambda obj: obj.blah + 100500)

Contributing

Contributions are welcome, and they are greatly appreciated! Every little bit helps, and credit will always be given.

Bug reports

When reporting a bug please include:

  • Your operating system name and version.
  • Any details about your local setup that might be helpful in troubleshooting.
  • Detailed steps to reproduce the bug.

Documentation improvements

repr could always use more documentation, whether as part of the official repr docs, in docstrings, or even on the web in blog posts, articles, and such.

Feature requests and feedback

The best way to send feedback is to file an issue at https://github.com/svetlyak40wt/python-repr/issues.

If you are proposing a feature:

  • Explain in detail how it would work.
  • Keep the scope as narrow as possible, to make it easier to implement.
  • Remember that this is a volunteer-driven project, and that code contributions are welcome :)

Development

To set up python-repr for local development:

  1. Fork python-repr (look for the “Fork” button).

  2. Clone your fork locally:

    git clone git@github.com:your_name_here/python-repr.git

  3. Create a branch for local development:

    git checkout -b name-of-your-bugfix-or-feature

    Now you can make your changes locally.

  4. When you’re done making changes, run all the checks, doc builder and spell checker with tox one command:

    tox

  5. Commit your changes and push your branch to GitHub:

    git add .
git commit -m "Your detailed description of your changes."
git push origin name-of-your-bugfix-or-feature

  6. Submit a pull request through the GitHub website.

Pull Request Guidelines

If you need some code review or feedback while you’re developing the code just make the pull request.

For merging, you should:

  1. Include passing tests (run tox) [1].
  2. Update documentation when there’s new API, functionality etc.
  3. Add a note to CHANGELOG.rst about the changes.
  4. Add yourself to AUTHORS.rst.
[1]

If you don’t have all the necessary python versions available locally you can rely on Travis - it will run the tests for each change you add in the pull request.

It will be slower though ...

Tips

To run a subset of tests:

tox -e envname -- py.test -k test_myfeature

To run all the test environments in parallel (you need to pip install detox):

detox

Authors

Changelog

0.3.0 (2016-06-20)

  • Now make_repr can be used for recursive datastructures.

0.2.1 (2016-06-19)

  • Documentation improved.

0.2.0 (2016-06-19)

  • Better handling of nested datastructure.
  • Callables as source of the attribute’s value.
  • Some documentation.

0.1.0 (2016-06-09)

  • First release on PyPI.

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