C#程序员学习 Python
孙广东 2016.1.1
交互：
C# 执行Python代码：
http://stackoverflow.com/questions/11779143/run-a-python-script-from-c-sharp
反着来：
http://stackoverflow.com/questions/3260015/run-a-c-sharp-application-from-python-script
Python语言的特点：
高级语言
内置电池（大量的标准库）
解释型（有时JIT编译）
面向对象（尤其是Python 3）
强类型动态语义
语法强调可读性
支持重用通过模块和包
Python程序的“形状” ：
Python定义代码块（在Python中使用 空格 和 冒号）。
看一个 Demo：
import random
def get_days():
# List days = new List();
# days[]
days = ['mon','tues','wed','thurs','fri','sat','sun']
return days
def get_random_report():
weather = ['sunny', 'lovely','cold']
return weather[ random.randint(0, len(weather) - 1)]
def main():
days = get_days()
for day in days:
report = get_random_report()
print("On {0} it will be {1}.".format(day, report))
if __name__ == "__main__":
main() C# 都有什么呢？
一、 Everything is an object (一切皆对象)
C# ：
class Document: object
{
public void Serialize()
{
// ...
}
public override string ToString()
{
return "I am a document ";
}
}Python：
class Document(object):
def serialize(self):
print("太好了！")
def __str__(self):
return "I am a document."
二、IEnumerable + foreach loops
C# :
int[] numbers = new[] {1, 2, 3, 4, 5, 6};
foreach (var n in numbers)
{
Console.Write(n + ",");
}class ShoppingCart : IEnumerable>
{
List> cartItems = new List>();
public void Add(string name, float price)
{
cartItems.Add(new Tuple(name, price));
}
public IEnumerator> GetEnumerator()
{
return cartItems.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return cartItems.GetEnumerator();
}
} Python :
numbers = [1, 2, 3, 4, 5, 6]
for n in numbers:
print(n, end=',')
for v in enumerate(numbers):
print(v, end=',')
for index, k in enumerate(numbers):
print(k, end=',')class CarItem:
def __init__(self, name, price):
self.price = price
self.name = name
def __repr__(self):
return "({0}, ${1})".format(self.name, self.price)
class ShoppingCart:
def __init__(self):
self.__items = []
def add(self, cart_item):
self.__items.append(cart_item)
def __iter__(self):
return self.__items.__iter__()
print()
print()
cart = ShoppingCart()
cart.add(CarItem("CD", 19.99))
cart.add(CarItem("Record", 17.99))
for item in cart.items:
print(item)
三、Properties （int Age {get; set;}）
C# :
class ShoppingCart
{
List> cartItems = new List>();
public float TotalPrice
{
get
{
float total = 0;
foreach (var item in cartItems)
{
total += item.Item2;
}
return total;
}
}
} Python :
class ShoppingCart: @property def total_price(self): total = 0.0 for item in self.__items: total += item.price return total
print("Total price is ${0:,}".format(cart.total_price))
四、Anonymous types （匿名类型）
C#：
public static void Main(String[] args)
{
var o = new
{
Id = 2,
Registered = true
};
Console.WriteLine(o);
if (o.Registered)
{
Console.WriteLine("They are registered...");
}
}python：
class AnonObject(dict):
__getattr__ = dict.get
__setattr__ = dict.__setitem__
person = {
"name": "Michael",
"age": 40
}
anonPerson = AnonObject(name = "Michael", age=40)
print(anonPerson)
print(anonPerson["name"])
print(anonPerson.name)
print(anonPerson.age)五、Lambda expressions
C#:
private static IEnumerable FindNumbers(Predicate predicate)
{
for (int i = 0; i < 100; i++)
{
if (predicate(i))
{
yield return i;
}
}
}
private IEnumerable nums = FindNumbers(n => n%11 == 0);
// [0, 11,22,33,44,55,66,77,88,99] python：
def get_numbers(limit, predicate):
for n in range(0, limit):
if predicate(n):
yield n
def divide_by_ll(n):
return n % 11 == 0
output = list(get_numbers(40, divide_by_ll))
print(output)def get_numbers(limit, predicate):
for n in range(0, limit):
if predicate(n):
yield n
# def divide_by_ll(n):
# return n % 11 == 0
output = list(get_numbers(40,lambda n : n % 11 ==0 ))
print(output)六、NuGET package management
七、Entity Framework 》ORMs