Python in 90 minutes

Python in 90 minutes
Bardia Heydari nejad

What is Python?
What normal people think What I think

Why Python?
• It’s multiiiiiiiiiiiiiiii purpose 😃
Web, GUI, Scripting, Data mining, Artificial intelligence ….
• It’s Readable 😊
No goddamn semicolon;
• It’s Productive 😮
10 times faster than C too produce a software

about Python
• interpreted: no more compiling no more binaries
• object-oriented: but you are not forced
• strongly-typed: explicits are better than implicit
• dynamically-typed: simple is better than complex
• cross platform: everywhere that interpreted exists
• indenting is a must: beautiful is better than ugly
• every thing is object

Hello, world!
#include<iostream>
using namespace std;
int main()
{
cout<<“Hello, world!”;
return 0;
}
C++

Hello, world!
public class Program {
public static main(string[] argus){
System.out.println(“Hello, world!”);
}
}
Java

Hello, world!
<html>
<head>
<title>PHP Test</title>
</head>
<body>
<?php echo ‘<p>Hello, world!</p>’; ?>
</body>
</html>
PHP

Hello, world!
print “Hello, world!”
Python

Operator
• +
• -
• *
• /
• //
• **
• %
• ==
• !=
• >
• <
• >=
• <=
• +=
• -=
• *=
• /=
• **=
• //=
• &
• |
• ^
• ~
• >>
• <<
• and
• or
• not
• in
• is

Variables
•int i = 1
•float f = 2.1
•bool b = False
•str s = ‘hi’
•list l = [1, 2, “hello again”, 4]
•tuple t = (True, 2.1)
•dict d = {1:”One”, 2:”Two”}
•set s = {“some”, “unique”, “objects”}

Variables - Assignment
>>> dummy_variable = 2
>>> dummy_variable = ‘hi’
>>> a, b = 2, 3
>>> a, b = b, a
int
main()
{
int
a
=
2,
b
=
3
,
k;
k
=
a;
a
=
b;
b
=
a;
return
0;
}
in c++

Variables - Casting
>>> float(1)
1.0
>>> str(1)
‘1’
>>> int(‘1’)
1
>>> list(1)
[1, ]
>>> list(‘hello’)
['h', 'e', 'l', 'l', ‘o']
>>> set([1, 0, 1, 1, 0, 1, 0, 0])
set([1, 0])

String
• concatenate
• slice
• find
• replace
• count
• capitalize

List
• slice
• concatenate
• sort
• append - pop - remove - insert

Condition
• if
• elif
• else

Loop
• while
• for
• else

Function
• Keyword arguments
• Default arguments
• Functions are objects

Object oriented
• Event classes are object
• Dynamically add attributes
• Static methods and attributes
• Property

Beyond OO
reflection/introspection
• type(obj)
• isinstance(obj, class)
• issubclass(class, class)
• getattr(obj, key) / hastattr(obj, key)

First class functions
• function assignment
• send function as parameter
• callable objects

Strategy pattern
 
class Player:  
def __init__(self, play_behavior):  
self.play_behavior = play_behavior  
 
def play(self):  
return self.play_behavior  
 
 
def attack():  
print("I attack”)  
 
attacker = Player(attack) .

Closure pattern
• function in function
def add(x):  
def add2(y):  
return x + y  
return add2
or with lambda
def add(x):  
return lambda y: x+y
• callable
class Add:  
def __init__(self, x):  
self.x = x  
 
def __call__(self, y):  
return self.x + y

Generator pattern
• subroutine vs co-routine
 
def get_primes(number):  
while True:  
if is_prime(number):  
yield number  
number += 1
 
 
def solve_number_10():  
total = 0  
for next_prime in get_primes(2):  
if next_prime < 2000000:  
total += next_prime  
else:  
break  
print(total)

Decorator pattern
def register_function(f):  
print("%s function is registered" % f.__name__)  
return f  
 
 
@register_function  
def do_dummy_stuff():  
return 1

Decorator pattern
add some tricks
def log(f):  
def logger_function(*args, **kwargs):  
result = f(*args, **kwargs)  
print("Result: %s" % result)  
return result  
 
return logger_function
 
 
@log  
return 1

Decorator pattern
add some tricks
def log(level=‘DEBUG'):  
def decorator(f):  
def logger_function(*args, **kwargs):  
result = f(*args, **kwargs)  
print("%s: %s" % (level, result))  
return result  
 
return logger_function  
 
return decorator  
 
 
@log(level=‘INFO')  
return 1

Complex syntax
One-line if:
print('even' if i % 2 == 0 else 'odd') 
One line for:
l = [num ** 2 for num in numbers] 
None or … :
value = dummy_function_may_return_none() or 0

Python in 90 minutes

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