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updated from Atlas

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This commit is contained in:
Luciano Ramalho
2015-04-15 04:48:25 -03:00
parent f4cdee2447
commit f86aee2785
78 changed files with 587 additions and 333 deletions
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37
descriptors/bulkfood_v1.py
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"""
A line item for a bulk food order has description, weight and price fields.
A ``subtotal`` method gives the total price for that line item::
>>> raisins = LineItem('Golden raisins', 10, 6.95)
>>> raisins.weight, raisins.description, raisins.price
(10, 'Golden raisins', 6.95)
>>> raisins.subtotal()
69.5
But, without validation, these public attributes can cause trouble::
# BEGIN LINEITEM_PROBLEM_V1
>>> raisins = LineItem('Golden raisins', 10, 6.95)
>>> raisins.subtotal()
69.5
>>> raisins.weight = -20 # garbage in...
>>> raisins.subtotal() # garbage out...
-139.0
# END LINEITEM_PROBLEM_V1
"""
# BEGIN LINEITEM_V1
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
# END LINEITEM_V1

63
descriptors/bulkfood_v2.py
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"""
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_V2
class LineItem:
def __init__(self, description, weight, price):
self.description = description
self.weight = weight # <1>
self.price = price
def subtotal(self):
return self.weight * self.price
@property # <2>
def weight(self): # <3>
return self.__weight # <4>
@weight.setter # <5>
def weight(self, value):
if value > 0:
self.__weight = value # <6>
else:
raise ValueError('value must be > 0') # <7>
# END LINEITEM_V2

64
descriptors/bulkfood_v2b.py
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"""
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

69
descriptors/bulkfood_v2prop.py
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"""
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 properties are stored in
instance attributes, created in each ``LineItem`` instance::
# BEGIN LINEITEM_V2_PROP_DEMO
>>> nutmeg = LineItem('Moluccan nutmeg', 8, 13.95)
>>> nutmeg.weight, nutmeg.price # <1>
(8, 13.95)
>>> sorted(vars(nutmeg).items()) # <2>
[('description', 'Moluccan nutmeg'), ('price', 13.95), ('weight', 8)]
# END LINEITEM_V2_PROP_DEMO
"""
# BEGIN LINEITEM_V2_PROP_FACTORY_FUNCTION
def quantity(storage_name): # <1>
def qty_getter(instance): # <2>
return instance.__dict__[storage_name] # <3>
def qty_setter(instance, value): # <4>
if value > 0:
instance.__dict__[storage_name] = value # <5>
else:
raise ValueError('value must be > 0')
return property(qty_getter, qty_setter) # <6>
# END LINEITEM_V2_PROP_FACTORY_FUNCTION
# BEGIN LINEITEM_V2_PROP_CLASS
class LineItem:
weight = quantity('weight') # <1>
price = quantity('price') # <2>
def __init__(self, description, weight, price):
self.description = description
self.weight = weight # <3>
self.price = price
def subtotal(self):
return self.weight * self.price # <4>
# END LINEITEM_V2_PROP_CLASS