Subset#

class ubermagutil.typesystem.Subset(name=None, **kwargs)#

Descriptor allowing setting attributes only with a subset of a predefined set.

Parameters:
  • sample_set (any type) – Defines the set of allowed values.

  • unpack (bool) – If True, value is unpacked as set(value).

Raises:

ValueError – If value is not a subset sample_set.

Example

  1. Usage of Subset descriptor.

>>> import ubermagutil.typesystem as ts
...
>>> @ts.typesystem(myattribute=ts.Subset(sample_set='xyz', unpack=True))
... class DecoratedClass:
...     def __init__(self, myattribute):
...         self.myattribute = myattribute
...
>>> dc = DecoratedClass(myattribute='yx')
>>> dc.myattribute = 'zyyyyx'  # valid set
>>> dc.myattribute = 'a'  # invalid set
Traceback (most recent call last):
    ...
ValueError: ...

Note

This class was derived from ubermagutil.typesystem.Descriptor and inherits its functionality.

See also

Descriptor


Methods

__delete__

Deleting the decorated class attribute is never allowed and AttributeError is raised.

__dir__

Default dir() implementation.

__eq__

Return self==value.

__repr__

Return repr(self).

__set__

If self.const=True, changing the value of a decorated class attribute after the initial set is not allowed.


__set__(instance, value)#

If self.const=True, changing the value of a decorated class attribute after the initial set is not allowed.

Raises:

AttributeError – If changing the value of a decorated class attribute is attempted.

Example

  1. Changing the value of a constant decorated class attribute.

>>> import ubermagutil.typesystem as ts
...
>>> @ts.typesystem(myattribute=ts.Descriptor(const=True))
... class DecoratedClass:
...     def __init__(self, myattribute):
...         self.myattribute = myattribute
...
>>> dc = DecoratedClass(myattribute="John Doe")
>>> dc.myattribute
'John Doe'
>>> dc.myattribute = 'Jane Doe'
Traceback (most recent call last):
   ...
AttributeError: ...