代写CSC1034: Lecture 4调试数据库编程

CSC1034: Lecture 4

Pizza

• Will finish with a worked example

As part of a larger project, building an online ordering system for a Pizza company, we need to design and implement a system for calculating the costs and some other features about a pizza. This system will allow you to build a pizza from a base and some toppings.

Pizza

• We need somewhere to put the data

• What features do pizza have?

•  One Base

•  Multiple toppings

Pizza: Iteration 1

•  Pizza, pizza bases, and pizza toppings all have names

•  Need a list of toppings, and one base import  collections

Base  =  collections.namedtuple( "Base" ,  "name")

Topping  =  collections.namedtuple( "Topping" ,  "name")

Pizza  =  collections.namedtuple( "Pizza" ,  "name  base  toppings")

p  =  Pizza  (

name= "Base"

base=Base(name= "Thin"), toppings=[

Topping("Olive"), Topping("Garlic")

]

)

print(p)

Pizza(name= ' Base ' ,  base=Base(name= ' Thin ' ),  toppings=[Topping(name= ' Olive ' ),  Topping(name= ' G

Pizza: Iteration 1

• I have used typed NamedTuples

•  Other possibilities

– list of ingredients, with base first,

– (non-named) tuple

– dictionary with two elements

– Class (next lectures!) import  collections

Base  =  collections.namedtuple( "Base" ,  "name")

Topping  =  collections.namedtuple( "Topping" ,  "name")

Pizza  =  collections.namedtuple( "Pizza" ,  "name  base  toppings")

p  =  Pizza  (

name= "Base"

base=Base(name= "Thin"), toppings=[

Topping("Olive"), Topping("Garlic")

]

)

print(p)

Pizza(name= ' Base ' ,  base=Base(name= ' Thin ' ),  toppings=[Topping(name= ' Olive ' ),  Topping(name= ' G

•  Points to note

•  Have test within file not in test, because it’s easier to show

Pizza:  Customer Reflections

• We’d like to be able to add a price

•  Output is a bit ugly

Pizza: Iteration 2

• Add pizza_price function

• Add pizza_report function

• Add price attribute to Base and Topping import  collections  import  collections

Base  =  collections.namedtuple("Base",  "name")             |  Base  =  collections .namedtuple("Base",

Topping  =  collections.namedtuple("Topping",  "name")             |

Topping  =  collections.namedtuple("Topping",  "name  price")

Pizza  =  collections.namedtuple("Pizza",  "name  base  toppings") Pizza  =  collections.namedtuple("Pizza",  "name  base  toppings")

>def  pizza_price(p):

>      return  p.base.price  +  sum(t.price  for  t  in  p.toppings) >

>def  pizza_report(p):

>        return  """Pizza:  {name} >Base:

>\t{base}\t\t\t:{baseprice: .2f}

>Toppings:   >{toppings} >

>Total:\t{total: .2f} >""" .format(

>       name=p .name,

>       base=p.base .name,

>       baseprice=p.base .price,

>        toppings="\n" .join(["\t{}\t\t\t:{: .2f}" .format(t.name,  t . >                                               for  t  in  p.toppings]),

>        total=  pizza_price(p) >)

p  =  Pizza  (  p  =  Pizza  (

name="Base",            |          name="SimplePizza",

base=Base(name="Thin"),           |          base=Base(name="Thin",  price=1.20),

toppings=[          toppings=[

Topping("Olive"),          |                  Topping("Olive",  price=0.70),

Topping("Garlic")            |               Topping("Garlic",  price=0.70)

]          ] )  )

print(p)           |  print(pizza_report(p))

Pizza: Iteration 2

import  collections

Base  =  collections.namedtuple( "Base" ,  "name  price")

Topping  =  collections.namedtuple( "Topping" ,  "name  price")

Pizza  =  collections.namedtuple( "Pizza" ,  "name  base  toppings")

def pizza_price(p):

return p.base .price  +  sum(t.price for t in p.toppings)

def pizza_report(p):

return """Pizza:  {name} Base:

\t{base}\t\t\t:{baseprice:.2f}

Toppings:   {toppings}

Total:\t{total:.2f}

""" .format(

name=p .name,

base=p.base .name,

baseprice=p.base .price,

toppings="\n" .join(["\t{}\t\t\t:{: .2f}" .format(t.name,  t.price) for t in p.toppings]),

total=  pizza_price(p) )

p  =  Pizza  (

name= "SimplePizza"

base=Base(name= "Thin",  price=1.20), toppings=[

Topping("Olive",  price=0.70), Topping("Garlic",  price=0.70)

] )

print(pizza_report(p))

Pizza:  SimplePizza Base:

Thin  :1 .20

Toppings:

Olive  :0 .70   Garlic  :0 .70

Total:  2 .60

•  Use generator expression because why not?

•  format within a format is baroque

– I can’t find an easier way

Pizza:  Customer Reflections

•  Do I have to put the prices for the ingredients in every time?

• Is the pizza veggie or not?

Pizza: Iteration 3

• Add veggie attribute to Topping

• Add pizza_veggie function

•  Update pizza report function

• Add catalogue of toppings and bases

import  collections  import  collections

Base  =  collections .namedtuple("Base",  "name  price")  Base  =  collections .namedtuple("Base",  "

Topping  =  collections.namedtuple("Topping",  "name  price")         |

Topping  =  collections .namedtuple("Topping",  "name  price  veggi Pizza  =  collections.namedtuple("Pizza",  "name  base  toppings") Pizza  =  collections.namedtuple("Pizza",  "name  base  toppings")

def  pizza_price(p):  def  pizza_price(p):

return  p.base.price  +  sum(t.price  for  t  in  p.toppings)        return  p.base.price  +  sum(t.

>def  pizza_veggie(p):

>      return  all(t.veggie  for  t  in  p.toppings) >

def  pizza_report(p):  def  pizza_report(p):

return  """Pizza:  {name}        return  """Pizza:  {name} Base:  Base:

\t{base}\t\t\t:{baseprice: .2f}  \t{base}\t\t\t:{baseprice: .2f}

Toppings:  Toppings:

{toppings}  {toppings}

Total:\t{total: .2f}  Total:\t{total: .2f} >

>{veggie}

""" .format(  """ .format(

name=p.name,        name=p .name,

base=p.base.name,       base=p.base .name,

baseprice=p.base.price,       baseprice=p.base .price,

toppings="\n" .join(["\t{}\t\t\t:{: .2f}" .format(t.name,  t . toppings="\n" .join(["\t{}\t\t\t:{: .2f}" .format(t.name,  t .

for  t  in  p.toppings]),                                               for  t  in  p.toppings]) total=  pizza_price(p)              |          total=pizza_price(p),

>        veggie="Is  Vegetarian"  if  pizza_veggie(p)  else  "Is  Not  Ve >)

>

>base  =  {

>       "thin":  Base(name="Thin",  price=1.20),

>       "thick":  Base(name="Thick",  price=1.50),

>       "stuffed":  Base(name="Stuffed  Crust  Monstrosity",  price=2 >}

>

>topping  =  {

>       "olive":  Topping(name="Olive",  price=0.70),

>        "garlic":  Topping(name="Garlic",  price=0.70),

>       "asparagus":  Topping(name="Asparagus",  price=1.20),

>       "mozzarella":  Topping(name="Mozzarella",  price=0.70), >       "scamorza":  Topping(name="Scamorza",  price=1.00),

>       "tomato":  Topping(name="Tomato",  price=0.90),

>       "speck":  Topping(name="Speck",  price=2.00,  veggie=False), >}

> >

>##  Nearly  a  Marghertisa >margherita  =  Pizza  (

>       name="Margherta",   >       base=base["thin"], >       toppings=[

>             topping["tomato"],

>             topping["mozzarella"]

>        ] )  )

p  =  Pizza  (              |  with_speck  =  Pizza  (

name="SimplePizza",            |          name="Margherta  with  Speck",

base=Base(name="Thin",  price=1.20),           |         base=base["thin"], toppings=[          toppings=[

Topping("Olive",  price=0.70),          |               topping["tomato"],

Topping("Garlic",  price=0.70)            |               topping["mozzarella"],

>               topping["speck"]

]          ] )  )

print(pizza_report(p))              |

>print(pizza_report(margherita)) >print(pizza_report(with_speck))

Pizza: Iteration 3

import  collections

Base  =  collections.namedtuple( "Base" ,  "name  price")

Topping  =  collections.namedtuple( "Topping" ,  "name  price  veggie",  defaults=[True]) Pizza  =  collections.namedtuple( "Pizza" ,  "name  base  toppings")

def pizza_price(p):

return p.base .price  +  sum(t.price for t in p.toppings)

def pizza_veggie(p):

return all(t.veggie for t in p.toppings)

def pizza_report(p):

return """Pizza:  {name} Base:

\t{base}\t\t\t:{baseprice:.2f}

Toppings:   {toppings}

Total:\t{total:.2f}

{veggie}

""" .format(

name=p .name,

base=p.base .name,

baseprice=p.base .price,

toppings="\n" .join(["\t{}\t\t\t:{: .2f}" .format(t.name,  t.price) for t in p.toppings]),

total=pizza_price(p),

veggie= "Is  Vegetarian" if pizza_veggie(p) else "Is  Not  Vegetarian" )

base  =  {

"thin" :  Base(name= "Thin",  price=1.20),     "thick" :  Base(name= "Thick",  price=1.50),

"stuffed" :  Base(name="Stuffed  Crust  Monstrosity",  price=2.50) }

topping  =  {

"olive" :  Topping(name="Olive",  price=0.70),     "garlic" :  Topping(name="Garlic",  price=0.70),

"asparagus" :  Topping(name="Asparagus",  price=1.20),     "mozzarella" :  Topping(name="Mozzarella",  price=0.70), "scamorza" :  Topping(name="Scamorza",  price=1.00),

"tomato" :  Topping(name="Tomato",  price=0.90),

"speck" :  Topping(name="Speck",  price=2.00,  veggie=False), }

## Nearly  a Marghertisa

margherita  =  Pizza  (     name= "Margherta" ,   base=base["thin"], toppings=[

topping[ "tomato"],

topping[ "mozzarella"]

] )

with_speck  =  Pizza  (

name= "Margherta  with  Speck" , base=base["thin"],

toppings=[

topping[ "tomato"],

topping[ "mozzarella"], topping["speck"]

] )

print(pizza_report(margherita)) print(pizza_report(with_speck))

Pizza:  Margherta Base:

Thin  :1 .20

Toppings:

Tomato  :0 .90

Mozzarella  :0 .70

Total:  2 .80

Is  Vegetarian

Pizza:  Margherta  with  Speck Base:

Thin  :1 .20

Toppings:

Tomato  :0 .90

Mozzarella  :0 .70

Speck  :2 .00 Total:  4.80

Is  Not  Vegetarian

Pizza: Future Work

•  Proper test suite

• And Price report structure

• Add VAT

•  Report output a bit clunky

•  Move pizza_price/veggie/report to be methods

Thoughts

•  Module is now five years old

• Taught differently every year!

• Welcome feedback on how well it worked

– Especially combined online/in person lecture material

Thoughts

•  Hope that I have introduced you to software engineering culture

• You have touched on a lot of topics

• They will take a long time to master

Thoughts

•  Hope that you have enjoyed the material

•  Good luck and enjoy the rest of the module