Merge pull request #48 from akhundMurad/feat/core/35

**feat(factory): add reusable TypeID factories with caching**

Author: akhundMurad

tests/test_factory.py

@@ -0,0 +1,35 @@
+import pytest
+
+from typeid import TypeID, cached_typeid_factory, typeid_factory
+from typeid.errors import PrefixValidationException
+
+
+def test_typeid_factory_generates_typeid_with_prefix():
+    gen = typeid_factory("user")
+    tid = gen()
+
+    assert isinstance(tid, TypeID)
+    assert tid.prefix == "user"
+
+
+def test_typeid_factory_returns_new_ids_each_time():
+    gen = typeid_factory("user")
+    a = gen()
+    b = gen()
+
+    assert a != b
+
+
+def test_cached_typeid_factory_is_cached():
+    a = cached_typeid_factory("user")
+    b = cached_typeid_factory("user")
+    c = cached_typeid_factory("order")
+
+    assert a is b
+    assert a is not c
+
+
+def test_factory_invalid_prefix_propagates():
+    gen = typeid_factory("BAD PREFIX")
+    with pytest.raises(PrefixValidationException):
+        gen()

typeid/__init__.py

@@ -1,3 +1,12 @@
+from .factory import TypeIDFactory, cached_typeid_factory, typeid_factory
 from .typeid import TypeID, from_string, from_uuid, get_prefix_and_suffix
 
-__all__ = ("TypeID", "from_string", "from_uuid", "get_prefix_and_suffix")
+__all__ = (
+    "TypeID",
+    "from_string",
+    "from_uuid",
+    "get_prefix_and_suffix",
+    "TypeIDFactory",
+    "typeid_factory",
+    "cached_typeid_factory",
+)

typeid/factory.py

@@ -0,0 +1,40 @@
+from dataclasses import dataclass
+from functools import lru_cache
+from typing import Callable
+
+from .typeid import TypeID
+
+
+@dataclass(frozen=True, slots=True)
+class TypeIDFactory:
+    """
+    Callable object that generates TypeIDs with a fixed prefix.
+
+    Example:
+        user_id = TypeIDFactory("user")()
+    """
+
+    prefix: str
+
+    def __call__(self) -> TypeID:
+        return TypeID(self.prefix)
+
+
+def typeid_factory(prefix: str) -> Callable[[], TypeID]:
+    """
+    Return a zero-argument callable that generates TypeIDs with a fixed prefix.
+
+    Example:
+        user_id = typeid_factory("user")()
+    """
+    return TypeIDFactory(prefix)
+
+
+@lru_cache(maxsize=256)
+def cached_typeid_factory(prefix: str) -> Callable[[], TypeID]:
+    """
+    Same as typeid_factory, but caches factories by prefix.
+
+    Use this if you create factories repeatedly at runtime.
+    """
+    return TypeIDFactory(prefix)

typeid/typeid.py

@@ -1,31 +1,34 @@
 import uuid
 import warnings
-from typing import Optional
+from typing import Generic, Optional, TypeVar
 
 import uuid6
 
 from typeid import base32
 from typeid.errors import InvalidTypeIDStringException
 from typeid.validation import validate_prefix, validate_suffix
 
+PrefixT = TypeVar("PrefixT", bound=str)
 
-class TypeID:
-    def __init__(self, prefix: Optional[str] = None, suffix: Optional[str] = None) -> None:
+
+class TypeID(Generic[PrefixT]):
+    def __init__(self, prefix: Optional[PrefixT] = None, suffix: Optional[str] = None) -> None:
         suffix = _convert_uuid_to_b32(uuid6.uuid7()) if not suffix else suffix
         validate_suffix(suffix=suffix)
-        if prefix:
+
+        if prefix is not None:
             validate_prefix(prefix=prefix)
 
-        self._prefix = prefix or ""
-        self._suffix = suffix
+        self._prefix: Optional[PrefixT] = prefix
+        self._suffix: str = suffix
 
     @classmethod
-    def from_string(cls, string: str):
+    def from_string(cls, string: str) -> "TypeID":
         prefix, suffix = get_prefix_and_suffix(string=string)
         return cls(suffix=suffix, prefix=prefix)
 
     @classmethod
-    def from_uuid(cls, suffix: uuid.UUID, prefix: Optional[str] = None):
+    def from_uuid(cls, suffix: uuid.UUID, prefix: Optional[PrefixT] = None) -> "TypeID":
         suffix_str = _convert_uuid_to_b32(suffix)
         return cls(suffix=suffix_str, prefix=prefix)
 
@@ -35,7 +38,7 @@ def suffix(self) -> str:
 
     @property
     def prefix(self) -> str:
-        return self._prefix
+        return self._prefix or ""
 
     @property
     def uuid(self) -> uuid6.UUID: