Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Save more on your purchases now! discount-offer-chevron-icon
Savings automatically calculated. No voucher code required.
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Arrow up icon
GO TO TOP
Python 3 Object-Oriented Programming - Second Edition

You're reading from   Python 3 Object-Oriented Programming - Second Edition Building robust and maintainable software with object oriented design patterns in Python

Arrow left icon
Product type Paperback
Published in Aug 2015
Publisher Packt
ISBN-13 9781784398781
Length 460 pages
Edition 1st Edition
Languages
Arrow right icon
Author (1):
Arrow left icon
Dusty Phillips Dusty Phillips
Author Profile Icon Dusty Phillips
Dusty Phillips
Arrow right icon
View More author details
Toc

Table of Contents (15) Chapters Close

Preface 1. Object-oriented Design FREE CHAPTER 2. Objects in Python 3. When Objects Are Alike 4. Expecting the Unexpected 5. When to Use Object-oriented Programming 6. Python Data Structures 7. Python Object-oriented Shortcuts 8. Strings and Serialization 9. The Iterator Pattern 10. Python Design Patterns I 11. Python Design Patterns II 12. Testing Object-oriented Programs 13. Concurrency Index

Generators


Generator expressions are actually a sort of comprehension too; they compress the more advanced (this time it really is more advanced!) generator syntax into one line. The greater generator syntax looks even less object-oriented than anything we've seen, but we'll discover that once again, it is a simple syntax shortcut to create a kind of object.

Let's take the log file example a little further. If we want to delete the WARNING column from our output file (since it's redundant: this file contains only warnings), we have several options, at various levels of readability. We can do it with a generator expression:

import sys
inname, outname = sys.argv[1:3]

with open(inname) as infile:
    with open(outname, "w") as outfile:
        warnings = (l.replace('\tWARNING', '')
                for l in infile if 'WARNING' in l)
        for l in warnings:
            outfile.write(l)

That's perfectly readable, though I wouldn't want to make the expression much more complicated than that. We...

lock icon The rest of the chapter is locked
Register for a free Packt account to unlock a world of extra content!
A free Packt account unlocks extra newsletters, articles, discounted offers, and much more. Start advancing your knowledge today.
Unlock this book and the full library FREE for 7 days
Get unlimited access to 7000+ expert-authored eBooks and videos courses covering every tech area you can think of
Renews at $19.99/month. Cancel anytime