feat: add generic Value[T] base class for value objects

- Create Value[T] (frozen dataclass + ABC + Generic) in domain/framework/
- Migrate ClassifiedAdTitle and ClassifiedAdText to inherit Value[str]
- Standardize all value access via .value instead of type-specific fields

domain/framework/__init__.py

@@ -0,0 +1 @@
+from .value import Value as Value

domain/framework/value.py

@@ -0,0 +1,7 @@
+from abc import ABC
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)
+class Value[T](ABC):
+    value: T

domain/marketplace/classified_ad.py

@@ -28,23 +28,27 @@ from domain.marketplace.user_id import UserId
 class ClassifiedAd(Entity):
     id: ClassifiedAdId
     _ownerId: UserId
-    title: ClassifiedAdTitle = field(default_factory=lambda: ClassifiedAdTitle(title=""))
-    text: ClassifiedAdText = field(default_factory=lambda: ClassifiedAdText(text=""))
+    title: ClassifiedAdTitle = field(
+        default_factory=lambda: ClassifiedAdTitle(value="")
+    )
+    text: ClassifiedAdText = field(default_factory=lambda: ClassifiedAdText(value=""))
     price: Price = field(default_factory=lambda: Price(amount=Decimal("0.00")))
     state: ClassifiedAdState = ClassifiedAdState.Inactive
     _changes: tuple[DomainEvent, ...] = ()
 
     def __post_init__(self):
         if not self._changes:
-            object.__setattr__(self, '_changes', (
-                ClassifiedAdCreated(id=self.id.value, owner_id=self._ownerId.value),
-            ))
+            object.__setattr__(
+                self,
+                "_changes",
+                (ClassifiedAdCreated(id=self.id.value, owner_id=self._ownerId.value),),
+            )
 
     def _ensure_valid_state(self):
         errors = []
-        if not self.title.title:
+        if not self.title.value:
             errors.append("title")
-        if not self.text.text:
+        if not self.text.value:
             errors.append("text")
         if self.price.amount <= 0:
             errors.append("price")
@@ -57,9 +61,9 @@ class ClassifiedAd(Entity):
     def when(self, event: DomainEvent) -> Self:
         match event:
             case ClassifiedAdTitleChanged():
-                return replace(self, title=ClassifiedAdTitle(title=event.title))
+                return replace(self, title=ClassifiedAdTitle(value=event.title))
             case ClassifiedAdTextUpdated():
-                return replace(self, text=ClassifiedAdText(text=event.ad_text))
+                return replace(self, text=ClassifiedAdText(value=event.ad_text))
             case ClassifiedAdPriceUpdated():
                 return replace(self, price=Price(amount=event.price))
             case ClassifiedAdSentForReview():
@@ -70,10 +74,12 @@ class ClassifiedAd(Entity):
         return self.apply(ClassifiedAdSentForReview(id=self.id.value))
 
     def set_title(self, title: ClassifiedAdTitle) -> ClassifiedAd:
-        return self.apply(ClassifiedAdTitleChanged(id=self.id.value, title=title.title))
+        return self.apply(ClassifiedAdTitleChanged(id=self.id.value, title=title.value))
 
     def update_text(self, text: ClassifiedAdText) -> ClassifiedAd:
-        return self.apply(ClassifiedAdTextUpdated(id=self.id.value, ad_text=text.text))
+        return self.apply(ClassifiedAdTextUpdated(id=self.id.value, ad_text=text.value))
 
     def update_price(self, price: Price) -> ClassifiedAd:
-        return self.apply(ClassifiedAdPriceUpdated(id=self.id.value, price=price.amount))
+        return self.apply(
+            ClassifiedAdPriceUpdated(id=self.id.value, price=price.amount)
+        )

domain/marketplace/classified_ad_text.py

@@ -1,6 +1,8 @@
 from dataclasses import dataclass
 
+from domain.framework.value import Value
+
 
 @dataclass(frozen=True)
-class ClassifiedAdText:
-    text: str
+class ClassifiedAdText(Value[str]):
+    pass

domain/marketplace/classified_ad_title.py

@@ -1,10 +1,12 @@
 from dataclasses import dataclass
 
+from domain.framework.value import Value
+
 
 @dataclass(frozen=True)
-class ClassifiedAdTitle:
-    title: str
-
+class ClassifiedAdTitle(Value[str]):
     def __post_init__(self):
-        if len(self.title) > 100:
-            raise ValueError(f"Title cannot be longer than 100 characters: {self.title}")
+        if len(self.value) > 100:
+            raise ValueError(
+                f"Title cannot be longer than 100 characters: {self.value}"
+            )