From academia to the corporate world

In this introduction to programming with Python, we learn about the origins of the Python programming language and key concepts that every computer programmer should know.

Python: the origins story

In 1991 Guido van Rossum is working in the Netherlands on a project called AMOEBA, a distributed operating system. He creates Python from the ABC language and publishes version 0.9.0 on a Usenet.

Numerical Python is released in 1996. In 2001, the Python Software Foundation is created. The Python programming language has a phenomenal success and versions after version is released... A large selection of modules are available, annual symposiums take place.

Universities start teaching Python and more corporations adopt Python as the programming language of choice for their new applications.

A growing community of developers loves Python for its simplicity and its useful tools. Python seems to have all the features required to conquer the world. It has several interactive interpreters software and a large online documentation. Development is fast and incremental. Testing and debugging processes are made easy with well-rounded tools. Data analysis is also interactive and user-friendly.

This is how, in a relatively short time, the Python programming language has become the darling of the academic world due to its simplicity and wealth of tools.

The popularity of Python stems from its concise, simple and clear syntax

Python is an interpreted language, which means that the code is translated into machine language at execution time. However, it is quite fast for an interpreted language because the compiled code is first saved in bytcode, which can be saved in a memory cache. Many Python libraries are also optimized code written in C or C++.

The popularity of Python stems from its concise, simple and clear syntax. Significant indentation encourages good coding structure. Memory is automatically managed by a garbage collector to avoid burdening the programmer with the task of deleting obsolete memory and causing potentailly serious programming bugs.

Python is also strongly typed and dynamic (no type declaration) which means that the interpreter tries to guess the data type of a variable and enforces that data type thereafter.

Your first Python code with 'Hello World'

It is customary to start learning a programming language by writing 'Hello World!' with the language. Here how to write your first line of Python code:

# This Python program prints Hello, world!

print('Hello, world!')

Object-Oriented Programming with Python

Python has a powerful Object-Oriented model but it is not compulsory to use objects. Both procedural and Object-Oriented code are available.

In Python programming, classes, functions and methods are first-class objects which can be passed as parameters.

The Multifile structure of Python applications makes module integration and modification easier. This modular approach means that procedural code is easier to manage and Object Oriented Python is not absolutely necessary.

The strength of Python comes from a large number of tools available

Python has thousands of libraries available in almost every field. It's the programming language of choice in data science, machine learning and artificial intelligence due to the wealth of ready to use code written by top researchers in each field.

Python is very portable and runs programs on various devices from mobile phones to electronic components.

Let's now explain some fundamental concepts that every programmer should know.

What is a computer?

A computer is a deterministic automaton with eletronic components. Given a suite of instructions, a computer will produce an expected result. A computer can be given a variety of instructions to perform. Programming languages are designed to make those instructions more convenient to write for people. Over time engineers have created new programming languages to focus on a specific problem or to make programming even more accessible.

The main components of a computer:

• A microprocessor with Unit Control (UC), an arithmetic and logical unit, a clock and a fast cache memory.

• Volatile memory or RAM (Random Access Memory), containing the required instructions and information to execute programs. RAM is made of binary cells (bits) grouped in bytes (8 bits)

• Peripherals: input/output, permanent memory on hard drives, USB flash disks, ROM, etc. Network interfaces. Graphics cards, etc.

There are 2 types of computer programs:

There are two types of programs: The Operating System (OS) is the group of programs which manages material resources and software applications. It assists in the exchanges between the user and the computer. The textual interface of the operating system interprets keyboard commands. The graphical interface manages windows on the screen. Operating systems are typically multitasks and multi-users.

Software applications are modules dedicated to a specific task. They can be installed on top of the operating system. The code source of the software application controls its user interface and functions. When a piece of software is executed the computer has to interpret and execute the commands of the source code. Python is mostly used to write software applications.

A brief historic of programming languages

• 1950s: experimental approach: FORTRAN, LISP, COBOL and ALGOL
• 1960s: PL/1 Simula, SmallTalk and Basic
• 1970s: C, PASCAL, ADA and MODULA-2
• 1980s: C++, LabView, Eiffel, Perl and VisualBasic
• 1990s: Java, Tlc/Tk, Ruby, Python and Peripherals
• 2000s: C# and VB.NET

Only a few programming languages are still used on a wide scale and Python is one of the chosen few.

How Python code is executed?

Python program execution uses a mix of interpretation and compilation of the code. Python code is compiled into bytecode which is then interpreted into machine code. When a Python program is executed, the source code file (.py or pyw) is loaded to active memory. The Python compiler does the lexical, syntactic, and semantic analysis of the code, then produces bytecode before executing it.

To avoid repeating the code compilation phase, Python saves the bytecode programs in a file (.pyo or .pyc) and uses the bytecode file until a new version of the source code is available.

Compilation into bytecode is thus done automatically by Python without the user realizing what is happening in the background.

How software programs are organized?

Software engineering deals with designing and producing software applications. Several models can be implemented for organizing software instructions.

Procedural programming uses a top to bottom analysis or linear approach to write instructions. Algorithms are written in layers from top level logic to lower level sub logic. The top level logic executes the main actions in a logical order.

Object-Oriented programming groups program code into logical objects. Higher-level logic deals with conceptual objects which interact to produce software behavior.

Sub-level logic is contained into a definition of the object, called a class.

Blueprints of objects, called classes, are defined with functions (called methods) and attributes (characteristics of an object). Classes can derive their definition from a parent class according to the principle of inheritance. An object can change its behavior based on the parameters submitted to its methods, according to the principle of polymorphism.

What is an algorithm

An algorithm is a finite number of successive instructions executed over a finite period to achieve a goal.

A computer program is the translation of an algorithm into a language that a machine can interpret or compile into executable machine code.

Programs and modules

Software projects often have millions lines of code. Modules help organize code and save computer resources like processing and memory.

Computer programs with a modular architecture are written in several parts: the principal program and program modules or extensions.

Book a class with an expert mentor to discuss these concepts, learn by doing with practical exercises and share ideas.