That: Python Hidden Code

Table of Contents

• Easter Eggs
• Geek
• Idioms
• Less Known Feature
• Don't Do It
• Command Line
• Extend Python
• One Liner
• Quotes
• Jokes
• Tools
• Guides

Easter Eggs

1. Zen of Python

import this

2. Open Python xkcd link in browser

import antigravity

3. Braces for code block

from __future__ import braces

4. Print Hello world! to stdout

import __hello__

Geek

1. Using braces in Python

if x == 1: #{
    print('hello')
#}

2. Unicode variable names

ünÏcode = 'hello'

3. Default value

x = False
y = x or 5 # if x is False, y will hold the default value 5.

4. Log the message, if debug is True

debug and log('debug message.') # if debug is True, then the message will be logged.

5.

status_headers[:] = [status, headers]

6. Comment out portion

bottle.run(app, port=8891) #, debug=True, reloader=True)

7. Ellipses...

while ...:
    print(hello)

8. No more zero 0000

You can use exponents instead of typing long floating point numbers.

total = 1e4 # 10000.0

9. Rot13 cipher

import codecs
codecs.encode('abc', 'rot13') # or 'rot-13'

str.encode doesn't support rot13.

10. You can split the digit from string in encoding name on anything

utf8, utf-8 and utf_8 and even utf+_+8 is one thing.

11. Last result

>>> 5 + 5
>>> _
10

This only works in interactive interpreter.

12. Accessing private properties

class Hello:
    __name = 'Python'
Hello._Hello__name # accessing private property __name

Idioms

1. Reversing a sequence

greet = 'Hello'
greet[::-1]

2. Removing duplicate

nums = [1, 2, 2, 3]
set(nums)

This will produce an unordered set.

To convert it back to a list you can do the following, although the order will still be lost:

nums = [1, 2, 2, 3]
list(set(nums))

3. Element with index

list = ['hello', 'world']
for index, value in enumerate(list):
    print(index, value)
# 1 hello
# 2 world

Less Known Feature

1. She bang

#!/usr/bin/env python3

2. Declare encoding

# -*- coding: utf-8 -*-

or

# coding: uft8

3. self is not a keyword

We can use any name instead of self in class defination.

class Hello:
	def __init__(this, name):
		this.name = name

4. Python file as a module and script

if __name__ == '__main__':

5. Like if the other for, while and try have else statements too

while True:
	print('hello')
else:
	print('not hello')

6. Your own type

new_str_type = type('new_str_type', (str,), {})

7. *args and **kwargs

list = [1, 2]
dict = {'name': 'hello'}
def hello(one, two, name=None):
	pass
hello(*list, **dict)

Don't Do It

1. Don't use bare bone exception

try:
	int(input)
except: # instead use except TypeError:
	pass

2. Use None as default parameter

Be careful: Mutable default parameters may not behave the way you think.

def hello(items=[]):
    items.append('hello')
    return items
first = hello()
second = hello() # you will get ['hello', 'hello'] here

If you expect a new object every time, use None as the default instead:

def hello(items=None):
    if items is None:
        items = []
    items.append('hello')
    return items
first = hello()
second = hello() # now you get ['hello']

Command Line

1. Show month calendar

python -m "calendar" 2015 9

For options: python -m "calendar" --help

2. Starts a server

python -m http.server --bind 127.0.0.1 8080

For options: python -m http.server --help

Extend Python

1. Input cousin, output function

output = print

2. multiline function will remove the indent form the lines

multiline("""Hello, How are you?
             Hello, How are you?
             Hello, How are you?""") # the function will remove the indent.

This one is fake yet.

3. | command-line piping with Pipe module

[1, 2, 3] | add

4. Goto, Using goto module

if x == 1:
    goto .end

One Liner

Quotes

Jokes

Tools

1. Interactive Python

• ipython

2. Tool for installing Python packages

• pip

Guides

Contributors

License

Licensed under MIT.