attribute-mapping

attribute-mapping is a minimalistic Python library for attribute-based access to dictionaries and other mappings.

Compared to many other implementations of the same idea, going by names such as AttrDict and various others, this library is extremely minimal and free of cruft:

• Almost no API
• AttributeMapping instances do not pretend to be a dict
• Can be used with dict as well as other objects implementing the collections.abc.Mapping abstract base class
• No restrictions on key/attribute names
• No unpleasant surprises in behaviour or weird corner cases
• Modern code; Python 3.4+ only
• 100% test coverage

Installation

python -m pip install attribute-mapping

Usage

Make an AttributeMapping instance by passing a dictionary or another mapping:

from attribute_mapping import AttributeMapping

d = {"a": 1, "b": {"c": 2, "d": 3}}
x = AttributeMapping(d)

Now you can access the contents using attribute lookups:

x.a  # gives 1
x.b.c  # gives 2

x.foo = 123
hasattr(x, "foo")  # True
del x.foo

In addition to attribute access, subscription (__getitem__ and friends) and containment checks (in) also work:

x["a"]  # gives 1
x["b"]["c"]  # gives 2
x["foo"] = 123
"foo" in x  # True
del x["foo"]

However, there are no other dict-like methods or reserved names, so you can happily use attributes like keys and items:

x.items = [1, 2, 3]

Iteration yields (key, value) tuples, just like .items() on normal mappings would do:

for key, value in x:
    ...

Finally, to obtain the original object that was used for the AttributeMapping, use the built-in vars() function:

d = {"a": 1}
x = AttributeMapping(d)
vars(x) is d  # True

Caveats

The attribute names __class__ and __dict__ are reserved in Python. If you really must use these names, use x["__class__"] and x["__dict__"] instead.

Credits

This library is written by wouter bolsterlee (wbolster).

There are a gazillion similar implementations, so the author thanks the whole Python community for the inspiration to make yet another implementation of this idea.

Version history

• 1.3.0 (2019-03-13)
  • Add support for len()
• 1.2.0 (2019-03-12)
  • Add support for (in)equality tests
• 1.1.0 (2019-03-09)
  • Add support for custom mappings
• 1.0.0 (2019-03-08)
  • Initial release

License

BSD; see LICENSE file for details.