python_introduction/learning_python3.md

What we'll learn

You'll learn three things at the same time so don't get discouraged if it feels a bit much at the start. Everybody's issues will be in these three different domains and at the beginning it can be difficult to differentiate between them. Keep this in mind, everybody has to go through this stage and the click comes at different times for different people but everybody clicks at some point! The three new things you'll learn:

1. the concepts of programming, most notably Object Orientated Programming (OOP)
2. the syntax of one particular language, in our case Python3
3. the tools needed to start programming in our language of choice

Within each of these topics there are subtopics but there are not bottomless! Below is a small overview of how I would subdivide them.

Concepts

The subtopics behind the concept of programming can be sliced (in no particular order) as follows:

• objects
• variables
• conditional logic
• functions
• loops

The concept behind these topics are the same in most languages, it's just how you write them that is different. This how is part of the syntax of the language.

Syntax

In computer science, the syntax of a computer language is the set of rules that defines the combinations of symbols that are considered to be correctly structured statements or expressions in that language. This applies both to programming languages, where the document represents source code, and to markup languages, where the document represents data. The syntax of a language defines its surface form.[1] Text-based computer languages are based on sequences of characters,

The quote above is taken shamelessly from wikipedia.

Tools

Writing code

Scripts are text files, plain and simple. So in order to write a Python3 script all we need is a text editor. Nano, vim, notepad++ all do a good job of editing plain text files but some make it easier than others. You've noticed that vim colors the code of a shell script no? One of the many features of an IDE is syntax highlighting. It colors things such as keywords which makes our life so much nicer when writing code. We'll come back to these features in a bit.

Running code

In order to run Python3 code you need the Python3 interpreter. This is because when you execute your script, the interpreter will read and execute each line of the text file line by line.

Most people who want to write and run Python3 code, or any language for that matter, will install an Integrated Development Environment to do so. There are no rules as to what has to be included for a program to qualify as an IDE but in my opinion they should include:

• syntax highlighting
• autocomplete
• goto commands such as goto definition, goto declaration, goto references
• automatic pair opening and closing
• builtin help navigation

There is a plethora of IDE's available and you can't really make a wrong choice here, but to make the overall learning curve a bit less steep we'll start out with a user friendly IDE, pycharm.

The python3 shell

TODO animated overview of the shell and the world of OOP

Installing pycharm

TODO

Your first project

TODO helloworld

Simple printing

String formatting

String replacement

Taking input

TODO say hello program

Functions can return something

Taking input and evaluation

TODO say hello plus ask for age

Conditional logic

Class string methods

Coding challenge - Celsius to Fahrenheit converter

Creating your own functions

TODO pretty_print

Functions that do something

Functions that return something

Writing your first library

TODO import pretty print

What are libraries?

How do we write libraries?

What is __name__ == "__main__"?

Using the standard library

TODO import random exercise