Exercise 7.9

tomaslucas · tomaslucas · commit b208588540ac · 2022-04-16T20:02:18.000+02:00
diff --git a/Work/stock.py b/Work/stock.py
@@ -1,5 +1,10 @@
+from typedproperty import *
+
 class Stock():
-    __slots__ = ('name', '_shares', 'price')
+    name = String('name')
+    shares = Integer('shares')
+    price = Float('price')
+
     def __init__(self, name, shares, price) -> None:
         self.name = name
         self.shares = shares
@@ -15,16 +20,6 @@ def sell(self, shares_sold):
     def __repr__(self):
         return f"Stock('{self.name}', {self.shares}, {self.price})"
 
-    @property
-    def shares(self):
-        return self._shares
-    
-    @shares.setter
-    def shares(self, value):
-        if not isinstance(value, int):
-            raise TypeError('Expected int')
-        self._shares = value
-
 
 class NewStock(Stock):
     def yow(self):
diff --git a/Work/typedproperty.py b/Work/typedproperty.py
@@ -0,0 +1,19 @@
+# typedproperty.py
+
+def typedproperty(name, expected_type):
+    private_name = '_' + name
+    @property
+    def prop(self):
+        return getattr(self, private_name)
+
+    @prop.setter
+    def prop(self, value):
+        if not isinstance(value, expected_type):
+            raise TypeError(f'Expected {expected_type}')
+        setattr(self, private_name, value)
+
+    return prop
+
+String = lambda name: typedproperty(name, str)
+Integer = lambda name: typedproperty(name, int)
+Float = lambda name: typedproperty(name, float)
