Coverage for sources/accretive/namespaces.py: 100%

1# vim: set filetype=python fileencoding=utf-8: 

2# -*- coding: utf-8 -*- 

3 

4#============================================================================# 

5# # 

6# Licensed under the Apache License, Version 2.0 (the "License"); # 

7# you may not use this file except in compliance with the License. # 

8# You may obtain a copy of the License at # 

9# # 

10# http://www.apache.org/licenses/LICENSE-2.0 # 

11# # 

12# Unless required by applicable law or agreed to in writing, software # 

13# distributed under the License is distributed on an "AS IS" BASIS, # 

14# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # 

15# See the License for the specific language governing permissions and # 

16# limitations under the License. # 

17# # 

18#============================================================================# 

19 

20 

21# pylint: disable=line-too-long 

22''' Accretive namespaces. 

23 

24Provides a namespace type that can grow but never shrink. Once an attribute is 

25set, it cannot be modified or removed. This provides a simple way to create 

26objects with named attributes that become immutable after assignment. 

27 

28The namespace implementation is modeled after :py:class:`types.SimpleNamespace` 

29but adds accretive behavior. Like :py:class:`types.SimpleNamespace`, it 

30provides a simple ``__repr__`` which lists all attributes. 

31 

32>>> from accretive import Namespace 

33>>> ns = Namespace( apples = 12, bananas = 6 ) 

34>>> ns.cherries = 42 # Add new attribute 

35>>> ns.apples = 14 # Attempt modification 

36Traceback (most recent call last): 

37 ... 

38accretive.exceptions.AttributeImmutabilityError: Cannot reassign or delete existing attribute 'apples'. 

39>>> del ns.bananas # Attempt deletion 

40Traceback (most recent call last): 

41 ... 

42accretive.exceptions.AttributeImmutabilityError: Cannot reassign or delete existing attribute 'bananas'. 

43''' 

44# pylint: enable=line-too-long 

45 

46 

47from . import __ 

48from . import objects as _objects 

49 

50 

51class Namespace( _objects.Object ): # pylint: disable=eq-without-hash 

52 ''' Accretive namespaces. ''' 

53 

54 def __init__( 

55 self, 

56 *iterables: __.DictionaryPositionalArgument[ __.H, __.V ], 

57 **attributes: __.DictionaryNominativeArgument[ __.V ], 

58 ) -> None: 

59 super( ).__init__( ) 

60 super( ).__getattribute__( '__dict__' ).update( 

61 *iterables, **attributes ) 

62 

63 def __repr__( self ) -> str: 

64 attributes = ', '.join( tuple( 

65 f"{key} = {value!r}" for key, value 

66 in super( ).__getattribute__( '__dict__' ).items( ) ) ) 

67 fqname = __.calculate_fqname( self ) 

68 if not attributes: return f"{fqname}( )" 

69 return f"{fqname}( {attributes} )" 

70 

71 def __eq__( self, other: __.a.Any ) -> __.ComparisonResult: 

72 mydict = super( ).__getattribute__( '__dict__' ) 

73 if isinstance( other, ( Namespace, __.SimpleNamespace ) ): 

74 return mydict == other.__dict__ 

75 return NotImplemented 

76 

77 def __ne__( self, other: __.a.Any ) -> __.ComparisonResult: 

78 mydict = super( ).__getattribute__( '__dict__' ) 

79 if isinstance( other, ( Namespace, __.SimpleNamespace ) ): 

80 return mydict != other.__dict__ 

81 return NotImplemented 

82 

83Namespace.__doc__ = __.generate_docstring( 

84 Namespace, 'description of namespace', 'instance attributes accretion' )