Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Free Learning
Arrow right icon
Secret Recipes of the Python Ninja
Secret Recipes of the Python Ninja

Secret Recipes of the Python Ninja: Over 70 recipes that uncover powerful programming tactics in Python

eBook
€8.99 €32.99
Paperback
€41.99
Subscription
Free Trial
Renews at €18.99p/m

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Table of content icon View table of contents Preview book icon Preview Book

Secret Recipes of the Python Ninja

Utilizing the Python Interpreter

In this chapter, we will talk about the Python interpreter, both as an interactive tool and for launching Python programs. Specifically, we will cover:

  • Launching Python environments
  • Utilizing Python command options
  • Working with environment variables
  • Making scripts executable
  • Modifying interactive interpreter startup
  • Alternative Python implementations
  • Installing Python on Windows
  • Embedding Python with other applications
  • Using alternative Python shells – IPython
  • Using alternative Python shells – bpython
  • Using alternative Python shells – DreamPie

Introduction

One of the benefits of the Python programming language is that it is interpreted, not compiled. This means that Python code is processed when it is called, rather than having to be pre-compiled before use. Because of this, interpreted languages generally have an interactive shell, allowing users to test code and otherwise have immediate feedback without having to create a separate source code file.

Of course, to get the most functionality out of a programming language, having permanent code files is necessary. When using an interactive prompt, the code lives in RAM; once the interactive session is closed, that code is lost. Thus, using an interactive prompt is a great way to quickly test programming ideas, but you wouldn't want to run a full-blown program from it.

This chapter will talk about using the Command Prompt to launch programs, as well as Python&apos...

Launching Python environments

By default, Python is installed on a computer with the Python interpreter included on the system path. This means that the interpreter will monitor the Command Prompt for any call to python

The most common usage for Python is to run a script. However, it may be desirable to launch a specific version of Python for a specific program.

How to do it...

  1. The most basic command to execute a Python program is as follows:
      $ python <script_name>.py
  1. The following examples show how to launch specific versions of Python, as needed:
      $ python2 some_script.py # Use the latest version of Python 2
$ python2.7 ... # Specifically use Python 2.7
$ python3 ... # Use...

Utilizing Python command options

When used non-interactively, the Python interpreter monitors the command line and parses all input before the command is actually executed. The following snippet shows all the possible options available when calling Python from the command line:

python [-bBdEhiIOqsSuvVWx?] [-c command | -m module-name | script | - ] [args] 

When working with a command line interface (CLI), examples of shell commands often show square brackets [] to indicate optional instructions. In this case, there are three groups of optional input that can be provided to the python command: generic options, interface options, and arguments.

How to do it...

  1. A number of options are available for the Python command-line...

Working with environment variables

Environment variables are part of operating systems and affect system operations. Python has Python-specific variables that affect how Python functions, that is, the behavior of the Python interpreter. While they are processed before command-line options, the command-line switches will override environment variables if there is a conflict.

How to do it...

  1. Environment variables are accessed via Python's os.environ.
  2. Because the environ object is a dictionary, you can specify a particular variable to view:
      >>> import os
>>> print(os.environ["PATH"])

/home/cody/anaconda3/bin:/home/cody/bin:/home/cody/
.local/bin:/usr/local/sbin:/usr/local...

Making scripts executable

Normally, executing a Python program requires typing python <program>.py. However, it is possible to make Python programs self-executing so they don't require typing python as the calling command.

How to do it...

  1. On *NIX systems, putting #!/usr/bin/env python as the first line of a program allows the program to be executable by referencing the location of Python on the user's PATH. Of course, this assumes Python is on the PATH; if not, then the program will have to be invoked like normal.
  2. After this has been added to the program, the file itself needs to be modified to make it executable, that is, $ chmod +x <program>.py.
  3. If you are using a terminal program that displays...

Modifying interactive interpreter startup

As mentioned in the Working with environment variables recipe, the PYTHONSTARTUP environment variable can be set to point to a file that contains commands that run prior to the Python interpreter starting up. This functionality is similar to .profile on *NIX shells.

As this startup file is only examined when interactive mode is used, there is no need to worry about trying to set configurations for running scripts (though later on we will show how to include the startup file in a script). The commands in this file are executed within the same namespace as the interactive interpreter, so there is no need to qualify functions or other imports with dot-nomenclature. This file is also responsible for making changes to interactive prompts: >>> (sys.ps1) and ... (sys.ps2).

...

Alternative Python implementations

Python has been ported to a number of other environments, such as Java and .NET. This means Python can be used in these environments like normal, but gains access to the APIs and code underpinnings for these environments.

Jython is used for Java integration, IronPython is used for the .NET framework, Stackless Python is available for enhanced threading performance, and MicroPython is for use with microcontrollers.

How to do it...

  1. To use Jython, a Java .jar file provides the installation executable. Two options are available for installation.
  2. Normal GUI installation is available by using the following:
      java -jar jython_installer-2.7.1.jar
  1. For console-based systems, such as headless...

Introduction


One of the benefits of the Python programming language is that it is interpreted, not compiled. This means that Python code is processed when it is called, rather than having to be pre-compiled before use. Because of this, interpreted languages generally have an interactive shell, allowing users to test code and otherwise have immediate feedback without having to create a separate source code file.

Of course, to get the most functionality out of a programming language, having permanent code files is necessary. When using an interactive prompt, the code lives in RAM; once the interactive session is closed, that code is lost. Thus, using an interactive prompt is a great way to quickly test programming ideas, but you wouldn't want to run a full-blown program from it.

This chapter will talk about using the Command Prompt to launch programs, as well as Python's functionality using the interactive shell. Special functionality with the Windows operating system will be discussed, and...

Launching Python environments


By default, Python is installed on a computer with the Python interpreter included on the system path. This means that the interpreter will monitor the Command Prompt for any call to python

The most common usage for Python is to run a script. However, it may be desirable to launch a specific version of Python for a specific program.

How to do it...

  1. The most basic command to execute a Python program is as follows:
      $ python <script_name>.py
  1. The following examples show how to launch specific versions of Python, as needed:
      $ python2 some_script.py # Use the latest version of Python 2
      $ python2.7 ... # Specifically use Python 2.7
      $ python3 ... # Use the latest version of Python 3
      $ python3.5.2 ... # Specifically use Python 3.5.2

How it works...

Calling python2 or python3 opens the latest installed version of the respective branch, whereas the other examples show how to invoke a specific version number. Regardless of whether a newer version...

Utilizing Python command options


When used non-interactively, the Python interpreter monitors the command line and parses all input before the command is actually executed. The following snippet shows all the possible options available when calling Python from the command line:

python [-bBdEhiIOqsSuvVWx?] [-c command | -m module-name | script | - ] [args]

When working with a command line interface (CLI), examples of shell commands often show square brackets [] to indicate optional instructions. In this case, there are three groups of optional input that can be provided to the python command: generic options, interface options, and arguments.

How to do it...

  1. A number of options are available for the Python command-line call. To enter interactive mode, call Python with no additional options:
      $ python
      Python 3.6.3 |Anaconda, Inc.| (default, Oct 13 2017, 12:02:49) 
      [GCC 7.2.0] on linux 
      Type "help", "copyright", "credits" or "license" for
      more information. 
      &gt...

Working with environment variables


Environment variables are part of operating systems and affect system operations. Python has Python-specific variables that affect how Python functions, that is, the behavior of the Python interpreter. While they are processed before command-line options, the command-line switches will override environment variables if there is a conflict.

How to do it...

  1. Environment variables are accessed via Python's os.environ.
  2. Because the environ object is a dictionary, you can specify a particular variable to view:
      >>> import os
      >>> print(os.environ["PATH"])
      /home/cody/anaconda3/bin:/home/cody/bin:/home/cody/
      .local/bin:/usr/local/sbin:/usr/local/bin:/usr
       /sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
  1. Adding a new variable is as simple as follows:
      >>> os.environ["PYTHONOPTIMIZE"] = "1"

How it works...

There are a large number of Python-specific environment variables available. Some of them are:

  • PYTHONHOME...

Making scripts executable


Normally, executing a Python program requires typing python <program>.py. However, it is possible to make Python programs self-executing so they don't require typing python as the calling command.

How to do it...

  1. On *NIX systems, putting #!/usr/bin/env python as the first line of a program allows the program to be executable by referencing the location of Python on the user's PATH. Of course, this assumes Python is on the PATH; if not, then the program will have to be invoked like normal.
  2. After this has been added to the program, the file itself needs to be modified to make it executable, that is, $ chmod +x <program>.py.
  3. If you are using a terminal program that displays files and directories in different colors depending on their modes, running the command ls on the directory where the file is located should show it with a different color than non-executable files.
  4. To execute the program, simply type ./<program>.py and the program will execute without...

Modifying interactive interpreter startup


As mentioned in the Working with environment variables recipe, the PYTHONSTARTUP environment variable can be set to point to a file that contains commands that run prior to the Python interpreter starting up. This functionality is similar to .profile on *NIX shells.

As this startup file is only examined when interactive mode is used, there is no need to worry about trying to set configurations for running scripts (though later on we will show how to include the startup file in a script). The commands in this file are executed within the same namespace as the interactive interpreter, so there is no need to qualify functions or other imports with dot-nomenclature. This file is also responsible for making changes to interactive prompts: >>> (sys.ps1) and ... (sys.ps2).

How to do it...

  1. To read an additional startup file from the current directory, the following example command shows how to code it in the global startup file (read_startup.py):
 ...
Left arrow icon Right arrow icon
Download code icon Download Code

Key benefits

  • •Access built-in documentation tools and improve your code.
  • •Discover how to make the best use of decorator and generator functions
  • •Enhance speed and improve concurrency by conjuring tricks from the PyPy project

Description

This book covers the unexplored secrets of Python, delve into its depths, and uncover its mysteries. You’ll unearth secrets related to the implementation of the standard library, by looking at how modules actually work. You’ll understand the implementation of collections, decimals, and fraction modules. If you haven’t used decorators, coroutines, and generator functions much before, as you make your way through the recipes, you’ll learn what you’ve been missing out on. We’ll cover internal special methods in detail, so you understand what they are and how they can be used to improve the engineering decisions you make. Next, you’ll explore the CPython interpreter, which is a treasure trove of secret hacks that not many programmers are aware of. We’ll take you through the depths of the PyPy project, where you’ll come across several exciting ways that you can improve speed and concurrency. Finally, we’ll take time to explore the PEPs of the latest versions to discover some interesting hacks.

Who is this book for?

Whether you’ve been working with Python for a few years or you’re a seasoned programmer, you’ll have a lot of new tricks to walk away with.

What you will learn

  • •Know the differences between .py and .pyc files
  • •Explore the different ways to install and upgrade Python packages
  • •Understand the working of the PyPI module that enhances built-in decorators
  • •See how coroutines are different from generators and how they can simulate multithreading
  • •Grasp how the decimal module improves floating point numbers and their operations
  • •Standardize sub interpreters to improve concurrency
  • •Discover Python's built-in docstring analyzer
Estimated delivery fee Deliver to Malta

Premium delivery 7 - 10 business days

€32.95
(Includes tracking information)

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : May 21, 2018
Length: 380 pages
Edition : 1st
Language : English
ISBN-13 : 9781788294874
Category :
Languages :
Tools :

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Estimated delivery fee Deliver to Malta

Premium delivery 7 - 10 business days

€32.95
(Includes tracking information)

Product Details

Publication date : May 21, 2018
Length: 380 pages
Edition : 1st
Language : English
ISBN-13 : 9781788294874
Category :
Languages :
Tools :

Packt Subscriptions

See our plans and pricing
Modal Close icon
€18.99 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
€189.99 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts
€264.99 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 120.97
Secret Recipes of the Python Ninja
€41.99
Python GUI Programming with Tkinter
€36.99
Functional Python Programming
€41.99
Total 120.97 Stars icon
Banner background image

Table of Contents

10 Chapters
Working with Python Modules Chevron down icon Chevron up icon
Utilizing the Python Interpreter Chevron down icon Chevron up icon
Working with Decorators Chevron down icon Chevron up icon
Using Python Collections Chevron down icon Chevron up icon
Generators, Coroutines, and Parallel Processing Chevron down icon Chevron up icon
Working with Python&#x27;s Math Module Chevron down icon Chevron up icon
Improving Python Performance with PyPy Chevron down icon Chevron up icon
Python Enhancement Proposals Chevron down icon Chevron up icon
Documenting with LyX Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

What is the delivery time and cost of print book? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela
What is custom duty/charge? Chevron down icon Chevron up icon

Customs duty are charges levied on goods when they cross international borders. It is a tax that is imposed on imported goods. These duties are charged by special authorities and bodies created by local governments and are meant to protect local industries, economies, and businesses.

Do I have to pay customs charges for the print book order? Chevron down icon Chevron up icon

The orders shipped to the countries that are listed under EU27 will not bear custom charges. They are paid by Packt as part of the order.

List of EU27 countries: www.gov.uk/eu-eea:

A custom duty or localized taxes may be applicable on the shipment and would be charged by the recipient country outside of the EU27 which should be paid by the customer and these duties are not included in the shipping charges been charged on the order.

How do I know my custom duty charges? Chevron down icon Chevron up icon

The amount of duty payable varies greatly depending on the imported goods, the country of origin and several other factors like the total invoice amount or dimensions like weight, and other such criteria applicable in your country.

For example:

  • If you live in Mexico, and the declared value of your ordered items is over $ 50, for you to receive a package, you will have to pay additional import tax of 19% which will be $ 9.50 to the courier service.
  • Whereas if you live in Turkey, and the declared value of your ordered items is over € 22, for you to receive a package, you will have to pay additional import tax of 18% which will be € 3.96 to the courier service.
How can I cancel my order? Chevron down icon Chevron up icon

Cancellation Policy for Published Printed Books:

You can cancel any order within 1 hour of placing the order. Simply contact customercare@packt.com with your order details or payment transaction id. If your order has already started the shipment process, we will do our best to stop it. However, if it is already on the way to you then when you receive it, you can contact us at customercare@packt.com using the returns and refund process.

Please understand that Packt Publishing cannot provide refunds or cancel any order except for the cases described in our Return Policy (i.e. Packt Publishing agrees to replace your printed book because it arrives damaged or material defect in book), Packt Publishing will not accept returns.

What is your returns and refunds policy? Chevron down icon Chevron up icon

Return Policy:

We want you to be happy with your purchase from Packtpub.com. We will not hassle you with returning print books to us. If the print book you receive from us is incorrect, damaged, doesn't work or is unacceptably late, please contact Customer Relations Team on customercare@packt.com with the order number and issue details as explained below:

  1. If you ordered (eBook, Video or Print Book) incorrectly or accidentally, please contact Customer Relations Team on customercare@packt.com within one hour of placing the order and we will replace/refund you the item cost.
  2. Sadly, if your eBook or Video file is faulty or a fault occurs during the eBook or Video being made available to you, i.e. during download then you should contact Customer Relations Team within 14 days of purchase on customercare@packt.com who will be able to resolve this issue for you.
  3. You will have a choice of replacement or refund of the problem items.(damaged, defective or incorrect)
  4. Once Customer Care Team confirms that you will be refunded, you should receive the refund within 10 to 12 working days.
  5. If you are only requesting a refund of one book from a multiple order, then we will refund you the appropriate single item.
  6. Where the items were shipped under a free shipping offer, there will be no shipping costs to refund.

On the off chance your printed book arrives damaged, with book material defect, contact our Customer Relation Team on customercare@packt.com within 14 days of receipt of the book with appropriate evidence of damage and we will work with you to secure a replacement copy, if necessary. Please note that each printed book you order from us is individually made by Packt's professional book-printing partner which is on a print-on-demand basis.

What tax is charged? Chevron down icon Chevron up icon

Currently, no tax is charged on the purchase of any print book (subject to change based on the laws and regulations). A localized VAT fee is charged only to our European and UK customers on eBooks, Video and subscriptions that they buy. GST is charged to Indian customers for eBooks and video purchases.

What payment methods can I use? Chevron down icon Chevron up icon

You can pay with the following card types:

  1. Visa Debit
  2. Visa Credit
  3. MasterCard
  4. PayPal
What is the delivery time and cost of print books? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela