Coverage for human_requests / base.py: 91%

1from __future__ import annotations 

2 

3from dataclasses import Field, field 

4from inspect import signature 

5from typing import Any, Callable, Generic, TypeVar, cast 

6 

7ParentT = TypeVar("ParentT") 

8FactoryParentT = TypeVar("FactoryParentT") 

9FactoryChildT = TypeVar("FactoryChildT") 

10 

11_API_CHILD_FACTORY_META = "human_requests_api_child_factory" 

12_UNSET = object() 

13 

14 

15class ApiChild(Generic[ParentT]): 

16 """ 

17 Base class for API child services that keeps a typed parent reference. 

18 """ 

19 

20 _parent: ParentT 

21 

22 def __init__(self, parent: ParentT) -> None: 

23 self._parent = parent 

24 

25 @property 

26 def parent(self) -> ParentT: 

27 return self._parent 

28 

29 

30class ApiParent: 

31 """ 

32 Dataclass mixin that initializes fields declared with `api_child_field`. 

33 """ 

34 

35 def __post_init__(self) -> None: 

36 dataclass_fields = getattr(self, "__dataclass_fields__", None) 

37 if not isinstance(dataclass_fields, dict): 

38 raise TypeError("ApiParent can only be used with dataclasses") 

39 

40 for dataclass_field in cast(dict[str, Field[Any]], dataclass_fields).values(): 

41 child_factory = cast( 

42 Callable[..., Any] | None, 

43 dataclass_field.metadata.get(_API_CHILD_FACTORY_META), 

44 ) 

45 if child_factory is None: 

46 continue 

47 

48 # Keep initialization idempotent if parent __post_init__ is called twice. 

49 if getattr(self, dataclass_field.name, _UNSET) is not _UNSET: 

50 continue 

51 

52 setattr(self, dataclass_field.name, _create_child(child_factory, self)) 

53 

54 

55def api_child_field( 

56 child_factory: Callable[..., FactoryChildT], 

57 *, 

58 repr: bool = False, 

59 compare: bool = False, 

60) -> FactoryChildT: 

61 """ 

62 Dataclass field helper for child API services initialized in `ApiParent.__post_init__`. 

63 """ 

64 

65 return cast( 

66 FactoryChildT, 

67 field( 

68 init=False, 

69 repr=repr, 

70 compare=compare, 

71 metadata={_API_CHILD_FACTORY_META: child_factory}, 

72 ), 

73 ) 

74 

75 

76def _create_child(child_factory: Callable[..., Any], parent: Any) -> Any: 

77 try: 

78 call_signature = signature(child_factory) 

79 accepts_parent = _can_bind_single_positional(call_signature, parent) 

80 except (TypeError, ValueError): 

81 # Fallback for callables without inspectable signatures. 

82 accepts_parent = True 

83 

84 child = child_factory(parent) if accepts_parent else child_factory() 

85 if not accepts_parent and isinstance(child, ApiChild): 

86 child._parent = parent 

87 return child 

88 

89 

90def _can_bind_single_positional(call_signature: Any, value: Any) -> bool: 

91 try: 

92 call_signature.bind(value) 

93 return True 

94 except TypeError: 

95 return False