Get in Touch with Python¶

This page is a slideshow!¶

Press ‘F10’ to start and stop
Press ‘space’ for current slide
Press ‘left’ and ‘right’ to go back and forth

Get in Touch with Python¶

Martin Bless

T3DD15 - TYPO3 Developer Days 2015 in Nuremberg

July 16-19, 2015

Agenda¶

Python: I’m talking about Python. So I bring some diversity and take you abroad.
What is it?: Python is a high level general programming language. Stable, common, powerful, available for all platforms.
Ansible, Saltstack, Sphinx, ...: You only know Python from the context of big and complex applications? Then you are missing something.
A great beginner’s language: It is often used in teaching, for children, by casual programmers. Don’t miss it. You can easily start. And it can take you anywhere.
As an experienced programmer: you will benefit definitely as well. Python should be part of your toolbox.
I love programming in Python: And that’s mainly for two reasons: Fun and productivity!

For whom?

This talk is for those who want to start with Python or those hoping to see a new trick.

We are going to

learn a bit about the basics
see interactive feature of Python
do a small meaningful example

IPython Notebook

It’s interactive and runs in the browser. I’ll try to give an impression of this phantastic tool.

And then?

It’s enough, I would say!

But we have options.

PyCharm?
Sphinx documentation tools for TYPO3?

Thank You!

Participants! Sponsors !! Helping hands !!! Organizers

of this marvellous and amazing event!

Fun and Productivity¶

Welcome!¶

Hello friends, I love programming in Python.
Why would somebody talk about Python? What’s so amazing about Python?
For me the answer can be given in two words: fun and productivity.
By fun I mean: Work is still work, but I tend to LIKE it.
By productivity I mean: I’m ten times faster. I can do jobs that I otherwise couldn’t.
I’m very much astonished that Python is mentioned so rarely in our community.
I’m afraid you’re missing something. So that’s the reason why I’m proposing the topic here.

Overall Goal¶

What am I saying?¶

I’m not saying “Do everything in Python”

My message is:¶

“You’ll gain a lot if you are ready for the first steps with Python and if you don’t avoid it.”

Programmers¶

“In the good old days”

you were a Php programmer. Or a Pascal programmer. Or a Java programmer.

Nowadays

a programmer is more thought of as an allrounder. It’s expected that you understand at least several of these:

Bash, C, Cobol, Coffeescript, Css, Haml, Haskell, Html, Java, Javascript, Pascal, Perl, Php, Python, Typescript, Typoscript, Xml, and so on.

Popularity: A Ranking of Programming Languages¶

Just the other day I saw this ranking of programming languages (June 2015):

RedMonk Q315 Programming Language Rankings

Source: http://sogrady-media.redmonk.com/sogrady/files/2015/07/lang-rank-615-wm.png

What’s most popular?

A Ranking of Programming Languages¶

Readings¶

Original article (english): The RedMonk Programming Language Rankings: June 2015
Article (T3N, german): About: Ranking of programming languages

Really another language? Oh must I?”¶

Doubts, hesitation, resistence ...¶

Why another language?
Don’t we have enough?
Haven’t we got enough problems already?
Install another tool? Why should I take the risk of screwing up my machine?

Is it worth the effort?¶

Yes!

Some Pro Arguments¶

Yes, it’s definitely worth the effort:

It’s not a matter of all or nothing
Python is easy to start with
You can start at any of many levels

And, NO

Installing Python will NOT screw up your machine

More Evangelism: What’s so great about Python?¶

Some personal notes¶

Documentation is great
Python is easy to learn and start with. Recommended for children!
Python code is very well readable. Something you write in pseudo code may very well be a valid Python program
Python code is very good to maintain
Python is very stable and backwards compatible
The core of the Python language by itself is very small. So the Python Language Reference shouldn’t be much of a problem. It describes syntax and language elements
The bigger task is to know the many and very good Library Functions of the The Python Standard Library. Keep that under your pillow!
Python is very interactive
There a many (easy) ways of debugging
Python has a nice and friendly community
Python is a preferred language for many scientists

More Evangelism¶

Two important things for me¶

Orthogonal and Regular: Python tries to do it “clean”, regular and “orthogonal”. For example, indexing and slicing have the same syntax for strings, lists and and list-like objects.
Libraries: Often I look into Python library function to understand complex issues. For example: What is a valid email format? Look into the Python “email” module for a lot of answers to that question.

Curious?¶

Hopefully you’re a bit curious by now¶

Find out if Python is installed already.

Get yourself a commandline and type: python --version

Hopefully you’ll see something like this:

If You Need To Install¶

Where to get Python from¶

Go to https://www.python.org/

Go to Downloads

Oops, wait:: What version should I choose?

Installation: Which version should I choose?¶

Python is in a transition phase¶

Read: https://wiki.python.org/moin/Python2orPython3

Installation¶

Linux¶

Go to https://www.python.org/

Go to Downloads

Python is most probably installed. If not, use the packet manager of your system:

sudo apt-get install python

Installation¶

Mac¶

Go to https://www.python.org/

Go to Downloads

I can’t say much about installing on a Mac.

Installation¶

Windows¶

Go to https://www.python.org/

Go to Downloads

Pick an installer for Windows:

Run the installer. Will install to C:\Python27 by default. Simply go with it. Or install to D:\Python27.

Tip

Make sure, the paths C:\Python27\Scripts and - maybe - C:\Python27\Tools\Scripts are in the path
Add .py to the PATHEXT system variable if you want to be able to start script program.py by just typing program.

First Contact¶

Let’s try something¶

Python opens in dialog mode:

$ python
Python 2.7.6 (default, Jun 22 2015, 17:58:13)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

>>> 1 + 1
2

>>> 'abc' + 'bcd'
'abcbcd'

>>> 3 * 5
15

>>> 'abc,' * 5
'abc,abc,abc,abc,abc,'

>>> ['a list'] * 3
['a list', 'a list', 'a list']

>>> exit()

First Contact: Interesting Aspects¶

Arbitrary long integers¶

>>> 2 ** 2
4
>>> 2 ** 22
4194304
>>> 2 ** 222
6739986666787659948666753771754907668409286105635143120275902562304L
>>> 2 ** 2222
7738385577878121270921913291177363957675805352044369150726746755451166643339
0225621118213792695021175190244951667322675647283977978393877115802136888227
6356848070794209358070102043443325352136545050000110534739684220468927252571
8545228637585111967234385629106091901532146690670721017896215421721054251511
3476510755470378003616234600251330288404641161878732714654916869730107991804
7772519772786759323456323386160178483395107203321577048282851869205647641463
3106982424173128829195665264713264067983600100179414810240875191907508744662
4702169205467746275821767903148850994094812935433097063308327801207416503803
3940046145844629478331113175706858291419937603163400966242304L

First Contact¶

How To Write Strings?¶

>>> 'string'
'string'

>>> "string"
'string'

>>> '''
... multiline string
... '''
'\nmultiline string\n'

>>> """multiline string"""
'multiline string'

>>> r'a raw string: C:\Python27'
'a raw string: C:\\Python27'

>>> u'unicode constants'
u'unicode constants'

First Contact¶

The Long Story about Strings and Literals¶

See the documentation:

Literals and String Literals in the Documentation

First Contact¶

Remember to do a tutorial¶

https://docs.python.org/2/tutorial/

Glorious Python - friendly and easy to learn

First Contact¶

Recommended Starter Page¶

Visit the About Python page

Some Basics¶

Statements¶

we don’t have curly braces for blocks: no { }
we don’t have dollar signs for variables: no $
we don’t have semicolons at the end of statements: no ;

Indentation instead!

Best practise: four blanks:

if 1 and 'say hello':
    msg = "Hello World!"
    print(msg)

Some Basics¶

Consistent Index and Slice Notation for Sequences¶

Lists will look very much like Json.

Tuples are like lists, but immutable.

Consistent:

>>> '0123456789'[2:5]   # string
'234'

>>> (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)[2:5]  # tuple
(2, 3, 4)

>>> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9][2:5]  # list
[2, 3, 4]

First Contact¶

Small Set of Builtin Functions¶

There is a rather small set of builtin functions plus the builtin types with objects methods

First Contact¶

Import Library Functions¶

Most of the functionality is in library function and needs to be imported. These modules have different namespaces by default:

>>> import math

>>> math
<module 'math' (built-in)>

>>> math.sqrt
<built-in function sqrt>

>>> math.sqrt(36)
6.0

>>> from math import sqrt

>>> sqrt
<built-in function sqrt>
>>> sqrt(36)
6.0

>>> exit()

Basics¶

Functional Parameters¶

def myfunc(a, b, args*, kwargs**):
    pass

myfunc(a, b)
myfunc(a, b, c, .., x)
myfunc(a, b, host='localhost', db='test')
myfunc(a, b, c, ..., x, host='localhost', db='test', ..., name=value)

Basics¶

What is falsy?¶

This is well defined in chapter Truth Value Testing.

False is:

None, False, Zero number, an empty sequence, an empty mapping and instances of classes, that return 0 by bool() oder len().

This means: You most often just need to write if thing: then ...:

result = myfunc()
if result:
   "do something"

Basics¶

Btw¶

I often write:

if 1 and 'explanation':
   'do something'

Because I can turn off a whole codeblock easily:

if 0 and 'explanation':
   'do something'

Easy, well readable, because highlighting remains, the compiler optimises this away.

Most notable change in Python 3: “print”¶

One of the most notable changes is that print is function in Python 3 while it’s a statement with special syntax in Python 2.

Import “the future” to use the futureproof print function in Python 2 already:

$ python
Python 2.7.6 (default, Jun 22 2015, 17:58:13)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

>>> print

>>> from __future__ import print_function
>>> print
<built-in function print>
>>> print("Hello world!")
Hello world!

About the nature of Python again¶

highly dynamic
dynamical typing
but NO automatic type conversion and “no magics”

You cannot use uninitialised variables:

>>> a
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'a' is not defined

Type conversion never happens implicitely:

>>> zero_string = '0'
>>> zero_string == 0
False

The Zen of Python¶

The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren’t special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one– and preferably only one –obvious way to do it.
Although that way may not be obvious at first unless you’re Dutch.
Now is better than never.
Although never is often better than right now.
If the implementation is hard to explain, it’s a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea – let’s do more of those!

Try Something Yourself¶

Go to Python.org and launch an interactive shell:

Try Something Yourself¶

Better: Try IPython from PythonAnywhere

What Can You Do With Python?¶

There’s a wide range of possible applications:

type some commands interactively
create shell commands
create complex shell suites
Objekt-Code einbinden
Create Gui-Application (sublime?)
integrate Python as scripting engines into other applications. Some games do this.
...

Production Boosters / Examples¶

Install the Sphinx Documentation Tools
Import an XML feed
Beautifulsoup
The ‘email’ module. By Barry Warsaw. You know Mailman?
Sphinx
IPython
A curated list of awesome Python frameworks, libraries and software

Beautiful Soup¶

Complete commandline program to list all links of a webpage:

#! /usr/bin/env python
# -*- coding: utf-8 -*-
import bs4, urllib2, sys

if len(sys.argv) != 2:
    print "usage: dumplinks.py <url>"
    exit(1)
url = sys.argv[1]
data = urllib2.urlopen(url).read()
soup = bs4.BeautifulSoup(data)
hits = soup.find_all('a')
for hit in hits:
    if hit.attrs.has_key('href'):
        print hit.attrs['href']

Writing Python Code¶

Source Code Encoding¶

#! /usr/bin/env python
# coding: ascii   <- assumed if nothing else specified

#! /usr/bin/env python
# coding: utf-8

Details

Writing Python Code¶

Generators are cool!¶

$ python
Python 2.7.6 (default, Jun 22 2015, 17:58:13)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> def gimme():
...     for item in ['Let me', 'show you', 'something']:
...         yield item
...     for item in [1, 2, 3]:
...         yield item
...
>>> for item in gimme():
...    print item
...
Let me
show you
something
1
2
3

IPython Interactive Computing¶

http://ipython.org

Editors, Tools, IDEs¶

If You Are on Windows: PythonWin!¶

Visit Python for Windows Extensions - pywin32

Editors, Tools, IDEs¶

Pycharm from Jetbrains!

IPython Interactive Computing¶

In a Terminal¶

http://ipython.org

Pycharm¶

Start a Terminal¶

Pycharm¶

Start Python in a Terminal Window in Pycharm¶

Pycharm¶

Start a Python Console¶

Pycharm¶

The Python Console in Pycharm¶

Just to mention¶

Jython¶

http://www.jython.org/

Language Comparisons¶

Should I learn Python or Ruby?