What Can We Learn From Python And JavaScript While Programming in C#

What can we learn from

Python and JavaScript

while programming in C# 4.0?

Introduction

Who I am?

---

First Name: Frederic
Last Name:  Torres
Web Site:   http://www.FredericTorres.net
State:      Massachusett

• I have been writing code since MS-DOS 2.0 on different continents.
• I write code in C# by day and in Python or JavaScript by night.

What about you ?

---

• Python, everyone.
  
  
  • IronPython 2.7 and tools for Visual Studio 2010 has been released.
• We all known JavaScript, right!
  
  
  • The World's Most Misunderstood Programming Language
  
  Douglas Crockford Web site about JavaScript

Why am I here?

---

Dynamic Languages - Python, Ruby, JavaScript.

    - Source Code Length

    - Readability

Python and Ruby

• The Pythonic way (Python Secret Weblog)
• Ruby is designed to make programmers happy

Peter Norvig from Google wrote a spell checker in 21 lines in Python How to Write a Spelling Corrector

import re, collections

def words(text): return re.findall('[a-z]+', text.lower()) 

def train(features):
    model = collections.defaultdict(lambda: 1)
    for f in features:
        model[f] += 1
    return model

NWORDS = train(words(file('big.txt').read()))

alphabet = 'abcdefghijklmnopqrstuvwxyz'

def edits1(word):
   splits     = [(word[:i], word[i:]) for i in range(len(word) + 1)]
   deletes    = [a + b[1:] for a, b in splits if b]
   transposes = [a + b[1] + b[0] + b[2:] for a, b in splits if len(b)>1]
   replaces   = [a + c + b[1:] for a, b in splits for c in alphabet if b]
   inserts    = [a + c + b     for a, b in splits for c in alphabet]
   return set(deletes + transposes + replaces + inserts)

def known_edits2(word):
    return set(e2 for e1 in edits1(word) for e2 in edits1(e1) if e2 in NWORDS)

def known(words): return set(w for w in words if w in NWORDS)

def correct(word):
    candidates = known([word]) or known(edits1(word)) or known_edits2(word) or [word]
    return max(candidates, key=NWORDS.get)

• Is there anything we can learn from programming Python and JavaScript and apply it in C#?
  
  
  • This is the question I have been thinking about.
  • And it is not just me!

A different way to code in C#

---

• Is there a different way to write code in C# in the air?
• 3 Samples

• ASP.NET MVC Syntax (Microsoft Product)

routes.MapRoute(
   "Default", // Route name
   "{controller}/{action}/{id}", // URL with parameters
   new { controller = "Home", action = "Index", id = UrlParameter.Optional } 
);

• Massive and Dapper : 2 small ORMs
  
  
  • Written in less than 400 lines of code each
  • Written by Rob Conery and Sam Saffron (from Stack Overflow)
  • Have been talked about on the hanselminutes podcast.

// Massive Syntax
var table = new Products();
table.Update( new { ProductName = "Chicken Fingers" } , 12);

var resultSet1 = persons.All(columns: "*", where: "ID >= @0", args: 1);
foreach(var p in resultSet1)
    Console.WriteLine(String.Format("ID:{0}, Name:{1}, {2}", p.ID, p.LastName, p.FirstName));                

//

• The Dapper library and reflection.

• Web Matrix (Microsoft Product)

How did I got involve in this

---

• The more experienced with Dynamic Languages, the more you will miss their syntaxes working in C#.
• Is there anything that we can do with?
  
  
  • Reflection
  • Generics
  • Anonymous types
  • Extension method
  • Lambda expression/statment
  • The keyword params
  • The keyword dynamic and the class DynamicObject

DynamicSugar.Net

• http://www.DynamicSugar.Net
  
  
  • A library providing methods and classes inspired by the dynamic languages Python and JavaScript
  • To write shorter and more readable source code in C# 4.0
  • On GitHub.com
  • On NuGet.org

It's all about Syntactic sugar.

Let's Start...

What can we learn about formatting string from JavaScript?

---

In C#

var firstName = "Fred";

Console.WriteLine(String.Format("Hello {0}",firstName));

In JavaScript

In JavaScript you may find this, which is not standard, but generally implemented via extension methods.

var firstName = "Fred";

print(String.format("Hello {0}",firstName));

print("Hello {0}".format(firstName));

print("Hello {firstName}".format( { firstName:"Fred" } ));

- Demo

What can we learn about formatting string from Python?

---

class Person(object):

  def __init__(self, name, age):
    self.Name = name
    self.Age  = age

  def Format(self, myFormat):
      return myFormat.format(**self.__dict__)

#######################################

p = Person("Fred", 45)
print p.Format("Name={Name}, Age={Age}")

- Demo

Object Literals [ ]

---

Python's List

i = 3

if i in [1,3,5]:
    print "in the list"

JavaScript's Array

This code is not standard JavaScript. The method Contains() and In() are
defined before this code as extension methods.

var i = 3;

if([1,3,5].Contains(i))
    console.log("in the list")

if(i.In([1,3,5]))
    console.log("in the list")

- Demo

What about a function returning multiple values?

---

What Python's syntax can say about that?

def ComputeValues(value):
    return True, 2.0*value, "Hello"

ok, amount, message = ComputeValues(2)

print ok:{0}, amount:{1}, message:{2}".format(ok, amount, message)

More about this

def ComputeValues(value):
    return True, 2.0*value, "Hello"

ok, amount, message = ComputeValues(2)

print "ok:%s, amount:%s, message:%s" % (ok, amount, message)


values = ComputeValues(2)

print "ok:%s, amount:%s, message:%s" % (values[0], values[1], values[2])

What JavaScript's syntax can say about that?

function ComputeValues(value) {

    return { ok:true, amount:2.0*value, message:"Hello" };
}

var r = ComputeValues(2);

print("ok:"             + r.ok);
print("amount:"         + r.amount);
print("message:"        + r.message);

- Demo

Object Literals { }

---

• Passing a populated dictionary to a function very common in Dynamic Languages.
• In Python and Ruby, there is a dedicated syntax just to do that.

This allow to pass an unlimited number of argument in very clear way, by defining the name and the value of each argument.

• JavaScript - an Ajax call with jQuery.

$.ajax( 
    {
        type    : "POST",
        url     : "some.php",
        data    : "name=John&location=Boston",
        success : function(msg){ alert( "Data Saved: " + msg ); }
    }
);

• Python

def MyFunction(**context):

    if context["debug"]:
        print "Debug on"

    if "America" in context["continent"]:
        print context["continent"]

MyFunction( debug=True,  continent="North America" )
MyFunction( debug=True,  continent="South America" )
MyFunction( debug=False, continent="Europe"        )

With C# 4.0

• Named parameters allow a similar syntax,
• The number of arguments is limited and have to be predefined.

void MyFunction(bool debug, string continent){
  // code
}

MyFunction(false, "Europe");

MyFunction(debug:false, continent:"Europe");

- Demo

Conclusion

---

• There are a lot of good concepts in Dynamic Languages
  
  
  • JavaScript is everywhere
  • Learn it
    
    
    • Douglas Crockford Web site about JavaScript
    
    
• C# is becoming more and more dynamic
  
  
  • More API are going to using these new language Constructs.
    
    
    • ASP.NET MVC, Web Matrix.
  • C# 5 will have a REPL (Read, Eval, Print, Loop)
  • C# 5 will have Eval() method (this should not be good)
• 2 Urls:
  
  
  • http://www.FredericTorres.Net
  • http://www.DynamicSugar.Net