ex 7.6

stock.py

@@ -1,5 +1,4 @@
 from structure import Structure
-from validate import PositiveFloat, PositiveInteger, String
 
 
 class Stock(Structure):
@@ -19,3 +18,9 @@ class Stock(Structure):
     def from_row(cls, row):
         rowdata = [func(val) for func, val in zip(cls._types, row)]
         return cls(*rowdata)
+
+
+if __name__ == '__main__':
+    from reader import read_csv_as_instances
+
+    portfolio = read_csv_as_instances('Data/portfolio.csv', Stock)

structure.py

@@ -1,3 +1,5 @@
+from collections import ChainMap
+
 from validate import Validator, validated
 
 
@@ -8,14 +10,25 @@ def validate_attributes(cls):
             validators.append(val)
         elif callable(val) and val.__annotations__:
             setattr(cls, name, validated(val))
-    cls._fields = tuple(val.name for val in validators)
+    cls._fields = tuple(v.name for v in validators)
     cls._types = tuple(getattr(v, 'expected_type', lambda x: x) for v in validators)
     if cls._fields:
         cls.create_init()
     return cls
 
 
-class Structure:
+class StructureMeta(type):
+    @classmethod
+    def __prepare__(meta, clsname, bases):
+        return ChainMap({}, Validator.validators)
+
+    @staticmethod
+    def __new__(meta, name, bases, methods):
+        methods = methods.maps[0]
+        return super().__new__(meta, name, bases, methods)
+
+
+class Structure(metaclass=StructureMeta):
     _fields = ()
 
     def __init_subclass__(cls):

validate.py

@@ -3,9 +3,15 @@ from functools import wraps
 
 
 class Validator:
+    validators = {}
+
     def __init__(self, name=None):
         self.name = name
 
+    @classmethod
+    def __init_subclass__(cls):
+        cls.validators[cls.__name__] = cls
+
     @classmethod
     def check(cls, value):
         return value
@@ -28,9 +34,9 @@ class Typed(Validator):
 
 
 _typed_classes = [
-    ('Integer', 'int'),
-    ('Float', 'float'),
-    ('String', 'str'),
+    ('Integer', int),
+    ('Float', float),
+    ('String', str),
 ]
 
 globals().update((name, type(name, (Typed,), {'expected_type': ty}))