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- Astropy v1.1.1 »
- Astropy Core Package Utilities (`astropy.utils`) »
- OrderedDescriptor

# OrderedDescriptor

class `astropy.utils.misc.``OrderedDescriptor`(*args, **kwargs)

  Bases: `object`

  Base class for descriptors whose order in the class body should be preserved. Intended for use in concert with the `OrderedDescriptorContainer` metaclass.

  Subclasses of `OrderedDescriptor` must define a value for a class attribute called `_class_attribute_`. This is the name of a class attribute on the container class for these descriptors, which will be set to an `OrderedDict` at class creation time. This `OrderedDict` will contain a mapping of all class attributes that were assigned instances of the `OrderedDescriptor` subclass, to the instances themselves. See the documentation for `OrderedDescriptorContainer` for a concrete example.

  Optionally, subclasses of `OrderedDescriptor` may define a value for a class attribute called `_name_attribute_`. This should be the name of an attribute on instances of the subclass. When specified, during creation of a class containing these descriptors, the name attribute on each instance will be set to the name of the class attribute it was assigned to on the class.

  Note

  Although this class is intended for use with descriptors (i.e. classes that define any of the `__get__`, `__set__`, or `__delete__` magic methods), this base class is not itself a descriptor, and technically this could be used for classes that are not descriptors too. However, use with descriptors is the original intended purpose.