ex 6.5

validate.py

@@ -1,3 +1,6 @@
+import inspect
+
+
 class Validator:
     def __init__(self, name=None):
         self.name = name
@@ -63,37 +66,23 @@ class NonEmptyString(String, NonEmpty):
     pass
 
 
-class Stock:
+class ValidatedFunction:
-    name = String()
+    def __init__(self, func):
-    shares = PositiveInteger()
+        self.func = func
-    price = PositiveFloat()
 
-    def __init__(self, name, shares, price):
+    def __call__(self, *args, **kwargs):
-        self.name = name
+        bound = inspect.signature(self.func).bind(*args, **kwargs)
-        self.shares = shares
+        if hasattr(self.func, '__annotations__'):
-        self.price = price
+            for arg in bound.arguments:
+                if arg in self.func.__annotations__ and issubclass(
+                    self.func.__annotations__[arg], Validator
+                ):
+                    self.func.__annotations__[arg].check(bound.arguments[arg])
+        result = self.func(*args, **kwargs)
+        return result
 
-    def __repr__(self):
-        return f"Stock({self.name!r}, {self.shares!r}, {self.price!r})"
 
-    def __eq__(self, other):
+if __name__ == '__main__':
-        if not isinstance(other, Stock):
+    def add(x: Integer, y: Integer):
-            return False
+        return x + y
-        return (self.name, self.shares, self.price) == (
+    add = ValidatedFunction(add)
-            other.name,
-            other.shares,
-            other.price,
-        )
-
-    @classmethod
-    def from_row(cls, row):
-        return cls(*row)
-
-    @property
-    def cost(self):
-        return self.shares * self.price
-
-    def sell(self, num):
-        self.shares -= num
-        if self.shares < 0:
-            self.shares = 0