Python for the C# developer

Python for the C# Developer

If you use C# and .NET, you may be surprised to find out how many of the features that you love also exist in Python (often first). Python is a wonderful language. It is a clean, high-level language which values readability over many trade-offs. You can build web applications serving billions of monthly page views.

https://www.youtube.com/watch?v=jj60geqaP08&list=PLQ176FUIyIUY5Ii58pzoZhS_3qIBL80nz&index=9&t=0s

Table of Contents:

Agenda The Python language in 10 minutes The 'shape' of a Python program What's awesome about C# and .NET?IDEs Great Debugger Everything is an Object IEnumerable + foreach loops Properties Anonymous objects Lambda expression LINQ NuGET package management Iterator methods / yield return ASP.NET MVC Entity Framework JIT compilation GUI Desginer Summary: Python for C# developer Q&A

Agenda

Introduce the basic of the Python language

Review what is awsome about C# and .NET

Explorer Python's version of each C# / .NET feature

The Python language in 10 minutes

High-level programming language

Batteries included (large standard library)

Interpreted (sometime JIT compiled)

Object-oriented (especially Python 3)

Strongly-typed with dynamic semantics

Syntax emphasizes readibity

Supports reuse through modules and packages

The 'shape' of a Python program

Python defines code blocks (known as suites in Python) using white space and colons.


def somemethod(name):
    if name == "Michael":
        print("Hi old friend")
    else:
        print("Nice to meet you")
        print("My name is ...")

def main():
    somemethod()

Pytnon language Demo


# wather.py

import random 

# public List<String> GetDays()
def get_days():
    # List<String> days = new List<String>();
    days = []

    days = ['mon', 'tues', 'wed', 'thurs', 'fri', 'sat', 'sun']

    return days

def get_random_report():
    weather = ['sunny', 'lovely', 'cold']

    return weather[random.randint0, 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()

What's awesome about C# and .NET?

System.Object Everything is an Object

IEnumerable + foreach loops

Class properties(int Age {get; set;})

Anonymous Type

Add reference

NuGET package management

Entity Framework / ORMs

Great debugging tools

ASP.NET MVC

LINQ

Visual Studio } IDEs

Side-by-side execution(isolation)

Iterator methods } yeild return

Anonymous methods / lamdas / closures

Base class libraries

JIT compilation

Resharper and IDE plugins

GUI designer

IDEs

Visual Sutdio

Python

PyCharm

Great Debugger

Python

All is beatiful

Everything is an Object


class Document : object
{
    public void Serialize()
    {
        // ...
    }

    public override string ToString()
    {
        return "I am a document";
    }
}

Python


class Document( object ):
    def serialize(self):
        # ...

   def __str__(self):
        return "I am a document."

IEnumerable + foreach loops


int[] numbers = new[] {1, 2, 3, 4, 5, 6};

foreach (var n in numbers)
{
    Console.write(n + ",");
}

Python


nums = [2, 3, 5, 7, 11, 13, 17, 19]

for n in nums:
    print(n, end=', ')


nums = [2, 3, 5, 7, 11, 13, 17, 19]

for v in enumerate(nums):
    print(v, end=', ')


nums = [2, 3, 5, 7, 11, 13, 17, 19]

for index,n in enumerate(nums):
    print(n, end=', ')


class ShoppingCart : IEnumerable<Tuple<string, float>>
{
    List<Tuple<string, float>> cartItems = 
        new List<Tuple<string, float>>();

    public void Add(string name, float price)
    {
        cartItems.Add(new Tuple<string, float>(name, price));
    }

    public IEnumerable<Tuple<string, float>> GetEnumerator()
    {
        return cartItems.GetEnumerator();
    }

    IEnumerator IEnumeratable.GetEnumerator()
    {
        return GetEnumerator();
    }
}

Python


class CartItem:
    def __init__(self, name, price):
        self.name = name
        self.price = price

    def __repr__(self):
        return "{0}, ${1}".format(self.name, self.price)

class ShoopingCart: 
    def __init__(self):
        self.__items = []

    def add(self, cart_item):
        self.itmes.append(cart_item)

    def __iter__(self):
        return self.__itmes.__iter__()


cart = ShoppingCart()
cart.add(CartTiem("CD", 19.99)
cart.add(CartTiem("Record", 17.99)

for item in cart.items:
    print(iteem)

Properties


class ShoppingCart : IEnumerable<Tuple<string, float>>
{
    List<Tuple<string, float>> cartItems = 
        new List<Tuple<string, float>>();

    public void Add(string name, float price)
    {
        cartItems.Add(new Tuple<string, float>(name, price));
    }

    public IEnumerable<Tuple<string, float>> GetEnumerator()
    {
        return cartItems.GetEnumerator();
    }

    IEnumerator IEnumeratable.GetEnumerator()
    {
        return GetEnumerator();
    }
}

class ShoppingCart
{
    get
    {
        float total = 0;
        foreach (var item in cartItems)
        {
            total += item.price;
        }
        return total;
    }
}

Console.WriteLine("Total price: {0}", cart.TotalPrice);

Python


class CartItem:
    def __init__(self, name, price):
        self.name = name
        self.price = price

    def __repr__(self):
        return "{0}, ${1}".format(self.name, self.price)

class ShoopingCart: 
    def __init__(self):
        self.__items = []

    def add(self, cart_item):
        self.itmes.append(cart_item)

    def __iter__(self):
        return self.__itmes.__iter__()

    @property
    def total_price(self):
        total = 0.0
        for item in self.__items:
            total += item.price

        return total


cart = ShoppingCart()
cart.add(CartTiem("CD", 19.99)
cart.add(CartTiem("Record", 17.99)

for item in cart.items:
    print(iteem)

print("Total price is {0:,", cart.total_price()}

Anonymous objects


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__

o = AnonObject(id = 42; registered = true)

print(o)

if o.registered:
    print("They are registered...")

Lambda expression


private static IEnumerable<int> FindNumbers(Predicate<int> predicate)
{
    for (int i = 0; i < 100; i++
    {
        if (predicate(i)) 
            yield return i;
    }
}

IEnumerable<int> nums = FindNumbers(n => n % 11 == 0)

Python


def numFilter(predicate):
    for i in range(100):
        if predicate(i):
            yield i


nums = numFilter(lambda n : n % 11 == 0)


def get_numbers(limit, predicate):
    for n in range(0, limit):
        if predicate(n):
            yield n

# def divide_by_11(n):
#     return n % 11 =


output = list(get_numbers(40, lambda n:  n % 11 == 0))

print(output)

LINQ


var older in people
    where p.age > 30
    orderedby p.age descending

    select new {age = p.age, name = p.name}

Python


class Person:
    def __init__(self, name, age, hobby):
        self.name = name
        self.age = age
        self.hobby = hobby


    def __repr__(self):
        return "{0} is {1} and {likes {2}".format(self.name, self.age, self.hobby)


people = [
    Person("Jeff", 50, "Biking"),
    Person("Michael", 40, "Biking"),
    Person("Sarah", 30, "Running"),
    Person("Tony", 24, "Jogging"),
    Person("Zoe", 12, "TV")
]

bikers = [
    p
    for p in people 
    if p.hobby == "biking"
]
biker.sort(key = lambda p: p.name
for b in bikers:
    print(b)

NuGET package management


Install-Package mongocsharpdriver

Python


 pip install pymongo

Iterator methods / yield return


private static IEnumerable<int> FibonacciGenerator()
{
    int current = 1;
    int next = 1;

    yield return current;
    while (true)
    {
        int temp = current + next;
        current = next;
        next = temp;
        yield return current;
    }
}

Python


def fibonacci_generator():
    current, nxt = 1, 1
    yield current

    while True:
        current, nxt = nxt, current + nxt
        yield current


def fibonacci():
    current = 0
    nxt = 1

    while True:
        current, nxt = nxt, current + nxt
        yield current

for n in fibonacci():
    if n > 200:
        break

print(n, end=', ')

ASP.NET MVC

ASP.NET

Python

Pyramid
django
Flask

Entity Framework

.net Entity Framework

Pythhon

SQL Alchemy

JIT compilation

JIT compliation via CLR

Python

pypy
IronPython

.NET Python on CLR

Jython

Java Python on JVM

GUI Desginer

Visual Studio

Python

PyQT (QT framework)

Summary: Python for C# developer

Python language is simple, concise and reable

Many parts of C# and .NET are awesome

Python often has equivalent features

sometimes nicer
sometimes less nice

Python has very capable IDE / Debugger in PyCharm

Q&A

Why use snake_case in Python?

It's Pythons' convention.
UpperCamelCase: class and many types...
snake_case: method and variables....