Initial commit

Solutions/5_3/reader.py

@@ -0,0 +1,32 @@
+# reader.py
+
+import csv
+
+def convert_csv(lines, converter, *, headers=None):
+    rows = csv.reader(lines)
+    if headers is None:
+        headers = next(rows)
+    return list(map(lambda row: converter(headers, row), rows))
+
+def csv_as_dicts(lines, types, *, headers=None):
+    return convert_csv(lines, 
+                       lambda headers, row: { name: func(val) for name, func, val in zip(headers, types, row) })
+
+def csv_as_instances(lines, cls, *, headers=None):
+    return convert_csv(lines,
+                       lambda headers, row: cls.from_row(row))
+
+def read_csv_as_dicts(filename, types, *, headers=None):
+    '''
+    Read CSV data into a list of dictionaries with optional type conversion
+    '''
+    with open(filename) as file:
+        return csv_as_dicts(file, types, headers=headers)
+
+def read_csv_as_instances(filename, cls, *, headers=None):
+    '''
+    Read CSV data into a list of instances
+    '''
+    with open(filename) as file:
+        return csv_as_instances(file, cls, headers=headers)
+

Solutions/5_3/stock.py

@@ -0,0 +1,51 @@
+# stock.py
+
+class Stock:
+    __slots__ = ('name','_shares','_price')
+    _types = (str, int, float)
+    def __init__(self, name, shares, price):
+        self.name = name
+        self.shares = shares
+        self.price = price
+
+    def __repr__(self):
+        # Note: The !r format code produces the repr() string
+        return f'{type(self).__name__}({self.name!r}, {self.shares!r}, {self.price!r})'
+
+    def __eq__(self, other):
+        return isinstance(other, Stock) and ((self.name, self.shares, self.price) ==
+                (other.name, other.shares, other.price))
+
+    @classmethod
+    def from_row(cls, row):
+        values = [func(val) for func, val in zip(cls._types, row)]
+        return cls(*values)
+
+    @property
+    def shares(self):
+        return self._shares
+    @shares.setter
+    def shares(self, value):
+        if not isinstance(value, self._types[1]):
+            raise TypeError(f'Expected {self._types[1].__name__}')
+        if value < 0:
+            raise ValueError('shares must be >= 0')
+        self._shares = value
+
+    @property
+    def price(self):
+        return self._price
+    @price.setter
+    def price(self, value):
+        if not isinstance(value, self._types[2]):
+            raise TypeError(f'Expected {self._types[2].__name__}')
+        if value < 0:
+            raise ValueError('price must be >= 0')
+        self._price = value
+
+    @property
+    def cost(self):
+        return self.shares * self.price
+
+    def sell(self, nshares):
+        self.shares -= nshares