Coverage for sources/accretive/classes.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''' Accretive classes. ''' 

22 

23 

24from __future__ import annotations 

25 

26from . import __ 

27from . import _annotations as _a 

28 

29 

30class Class( type ): 

31 ''' Accretive classes. ''' 

32 

33 def __new__( 

34 factory: _a.Type[ type ], 

35 name: str, 

36 bases: _a.Tuple[ type, ... ], 

37 namespace: _a.MutableMapping[ str, _a.Any ], 

38 docstring: str = None, 

39 **nomargs: _a.Any 

40 ) -> Class: 

41 if docstring: namespace[ '__doc__' ] = docstring 

42 return _a.cast( 

43 Class, 

44 super( ).__new__( factory, name, bases, namespace, **nomargs ) ) 

45 

46 def __delattr__( class_, name: str ) -> None: 

47 from .exceptions import IndelibleAttributeError 

48 raise IndelibleAttributeError( name ) 

49 

50 def __setattr__( class_, name: str, value: _a.Any ) -> None: 

51 from .exceptions import IndelibleAttributeError 

52 if hasattr( class_, name ): raise IndelibleAttributeError( name ) 

53 # Note: CPython cell class is not set in all circumstances. 

54 # When it is, then we use two-argument form. 

55 # Else, we use three-argument form. 

56 try: super( ).__setattr__( name, value ) 

57 except TypeError: 

58 super( ).__setattr__( # type: ignore[call-arg] 

59 class_, name, value ) # type: ignore[arg-type] 

60 

61Class.__doc__ = __.generate_docstring( 

62 Class, 

63 'description of class factory class', 

64 'class attributes accretion' 

65) 

66 

67 

68class ABCFactory( Class, __.ABCFactory ): # type: ignore[misc] 

69 ''' Accretive abstract base classes (ABC). ''' 

70 

71 def __setattr__( class_, name: str, value: _a.Any ) -> None: 

72 # Bypass accretion machinery for ABC magic attributes. 

73 if ( # pylint: disable=magic-value-comparison 

74 '__abstractmethods__' == name or name.startswith( '_abc_' ) 

75 ): 

76 __.ABCFactory.__setattr__( class_, name, value ) 

77 return 

78 super( ).__setattr__( name, value ) 

79 

80ABCFactory.__doc__ = __.generate_docstring( 

81 ABCFactory, 

82 'description of class factory class', 

83 'class attributes accretion', 

84 'abc attributes exemption', 

85) 

86 

87 

88__all__ = __.discover_public_attributes( globals( ) )