update from Atlas

Author: ramalho

descriptors/bulkfood_v2b.py

@@ -0,0 +1,64 @@
+"""
+
+A line item for a bulk food order has description, weight and price fields::
+
+    >>> raisins = LineItem('Golden raisins', 10, 6.95)
+    >>> raisins.weight, raisins.description, raisins.price
+    (10, 'Golden raisins', 6.95)
+
+A ``subtotal`` method gives the total price for that line item::
+
+    >>> raisins.subtotal()
+    69.5
+
+The weight of a ``LineItem`` must be greater than 0::
+
+    >>> raisins.weight = -20
+    Traceback (most recent call last):
+        ...
+    ValueError: value must be > 0
+
+No change was made::
+
+    >>> raisins.weight
+    10
+
+The check is also performed on instantiation::
+
+    >>> walnuts = LineItem('walnuts', 0, 10.00)
+    Traceback (most recent call last):
+        ...
+    ValueError: value must be > 0
+
+The proteced attribute can still be accessed if needed for some reason, such as
+white box testing)::
+
+    >>> raisins._LineItem__weight
+    10
+
+"""
+
+
+# BEGIN LINEITEM_V2B
+class LineItem:
+
+    def __init__(self, description, weight, price):
+        self.description = description
+        self.weight = weight
+        self.price = price
+
+    def subtotal(self):
+        return self.weight * self.price
+
+    def get_weight(self):  # <1>
+        return self.__weight
+
+    def set_weight(self, value):  # <2>
+        if value > 0:
+            self.__weight = value
+        else:
+            raise ValueError('value must be > 0')
+
+    weight = property(get_weight, set_weight)  # <3>
+
+# END LINEITEM_V2B

descriptors/bulkfood_v2prop.py

@@ -0,0 +1,58 @@
+"""
+
+A line item for a bulk food order has description, weight and price fields::
+
+    >>> raisins = LineItem('Golden raisins', 10, 6.95)
+    >>> raisins.weight, raisins.description, raisins.price
+    (10, 'Golden raisins', 6.95)
+
+A ``subtotal`` method gives the total price for that line item::
+
+    >>> raisins.subtotal()
+    69.5
+
+The weight of a ``LineItem`` must be greater than 0::
+
+    >>> raisins.weight = -20
+    Traceback (most recent call last):
+        ...
+    ValueError: value must be > 0
+
+No change was made::
+
+    >>> raisins.weight
+    10
+
+
+"""
+
+
+# BEGIN LINEITEM_V2_PROP
+def quantity(storage_name):  # <1>
+
+    @property  # <2>
+    def new_prop(self):
+        return self.__dict__[storage_name]  # <3>
+
+    @new_prop.setter
+    def new_prop(self, value):
+        if value > 0:
+            self.__dict__[storage_name] = value  # <4>
+        else:
+            raise ValueError('value must be > 0')
+
+    return new_prop  # <5>
+
+
+class LineItem:
+    weight = quantity('weight')  # <6>
+    price = quantity('price')  # <7>
+
+    def __init__(self, description, weight, price):
+        self.description = description
+        self.weight = weight
+        self.price = price
+
+    def subtotal(self):
+        return self.weight * self.price
+# END LINEITEM_V2_PROP

descriptors/bulkfood_v4prop.py

@@ -0,0 +1,76 @@
+"""
+
+A line item for a bulk food order has description, weight and price fields::
+
+    >>> raisins = LineItem('Golden raisins', 10, 6.95)
+    >>> raisins.weight, raisins.description, raisins.price
+    (10, 'Golden raisins', 6.95)
+
+A ``subtotal`` method gives the total price for that line item::
+
+    >>> raisins.subtotal()
+    69.5
+
+The weight of a ``LineItem`` must be greater than 0::
+
+    >>> raisins.weight = -20
+    Traceback (most recent call last):
+        ...
+    ValueError: value must be > 0
+
+No change was made::
+
+    >>> raisins.weight
+    10
+
+The value of the attributes managed by the descriptors are stored in
+alternate attributes, created by the descriptors in each ``LineItem``
+instance::
+
+    >>> raisins = LineItem('Golden raisins', 10, 6.95)
+    >>> sorted(dir(raisins))  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
+    [..., '_quantity_0', '_quantity_1', 'description',
+     'price', 'subtotal', 'weight']
+    >>> raisins._quantity_0
+    10
+    >>> raisins._quantity_1
+    6.95
+
+"""
+
+
+# BEGIN LINEITEM_V4_PROP
+def quantity():  # <1>
+    try:
+        quantity.counter += 1  # <2>
+    except AttributeError:
+        quantity.counter = 0  # <3>
+
+    storage_name = '_{}_{}'.format('quantity', quantity.counter)  # <4>
+
+    @property  # <5>
+    def prop(self):
+        return getattr(self, storage_name)
+
+    @prop.setter
+    def prop(self, value):
+        if value > 0:
+            setattr(self, storage_name, value)
+        else:
+            raise ValueError('value must be > 0')
+
+    return prop  # <6>
+
+
+class LineItem:
+    weight = quantity()  # <7>
+    price = quantity()
+
+    def __init__(self, description, weight, price):
+        self.description = description
+        self.weight = weight
+        self.price = price
+
+    def subtotal(self):
+        return self.weight * self.price
+# END LINEITEM_V4_PROP

descriptors/bulkfood_v5.py

@@ -0,0 +1,75 @@
+"""
+
+A line item for a bulk food order has description, weight and price fields::
+
+    >>> raisins = LineItem('Golden raisins', 10, 6.95)
+    >>> raisins.weight, raisins.description, raisins.price
+    (10, 'Golden raisins', 6.95)
+
+A ``subtotal`` method gives the total price for that line item::
+
+    >>> raisins.subtotal()
+    69.5
+
+The weight of a ``LineItem`` must be greater than 0::
+
+    >>> raisins.weight = -20
+    Traceback (most recent call last):
+        ...
+    ValueError: value must be > 0
+
+No change was made::
+
+    >>> raisins.weight
+    10
+
+The value of the attributes managed by the descriptors are stored in
+alternate attributes, created by the descriptors in each ``LineItem``
+instance::
+
+    >>> raisins = LineItem('Golden raisins', 10, 6.95)
+    >>> dir(raisins)  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
+    ['_NonBlank_0', '_Quantity_0', '_Quantity_1', '__class__', ...
+     'description', 'price', 'subtotal', 'weight']
+    >>> raisins._Quantity_0
+    10
+    >>> raisins._Quantity_1
+    6.95
+
+If the descriptor is accessed in the class, the descriptor object is
+returned:
+
+    >>> LineItem.price  # doctest: +ELLIPSIS
+    <model_v5.Quantity object at 0x...>
+    >>> br_nuts = LineItem('Brazil nuts', 10, 34.95)
+    >>> br_nuts.price
+    34.95
+
+The `NonBlank` descriptor prevents empty or blank strings to be used
+for the description:
+
+    >>> br_nuts.description = ' '
+    Traceback (most recent call last):
+        ...
+    ValueError: value cannot be empty or blank
+
+
+"""
+
+# BEGIN LINEITEM_V5
+import model_v5 as model  # <1>
+
+
+class LineItem:
+    description = model.NonBlank()  # <2>
+    weight = model.Quantity()
+    price = model.Quantity()
+
+    def __init__(self, description, weight, price):
+        self.description = description
+        self.weight = weight
+        self.price = price
+
+    def subtotal(self):
+        return self.weight * self.price
+# END LINEITEM_V5