Specificity, Selectors, and the Cascade: Applying CSS3 to Documents – #bookreview

Selectors, Specificity, and the Cascade: Applying CSS3 to Documents
Eric A. Meyer
(O’Reilly, paperbackKindle)

If you know some basic CSS but wonder how the “cascade” part of Cascading Style Sheets works, here is a useful guide.

Actually, this is a 73-page, two-chapter excerpt from the upcoming fourth edition of Eric A. Meyer’s CSS: The Definitive Guide. If you are learning CSS, dealing with CSS issues, or moving to CSS3, this small book can provide you with numerous how-to examples to apply to right now.

The first chapter focuses on “Selectors.” Selectors are not clearly defined at the beginning. But they generally are described elsewhere as “patterns” that can be used to select the element or elements you want to style in a document, such as headings of a certain font sizes or paragraphs with text in specific colors.

Fortunately, the first chapter’s code examples, descriptive paragraphs, and illustrations quickly clarify how to put selectors to work in a document. “[D]ocument structure and CSS selectors allow you to apply a wide variety of style to elements,” the author notes.

The second chapter’s topics are “Specificity and the Cascade.” And the initial technical definitions get a bit dense. For example: “When determining which values should apply to an element, a user agent must consider not only inheritance but also the specificity of the declaration, as well as the origin of the declarations themselves. The process of consideration is what’s known as the cascade.”

Uh, okay.

Once again, fortunately, the second chapter’s code samples, illustrations, and follow-up paragraphs quickly clarify what is going on. And they enable you to learn by doing, seeing the outcome, and applying what you’ve learned to documents of your own.

Si Dunn

Programming Google App Engine, 2nd Edition – An important how-to guide, updated – #programming #bookreview

Programming Google App Engine, 2nd Edition
Dan Sanderson

O’Reilly recently has published a new edition of Dan Sanderson’s Programing Google App Engine.  The new edition updates the 2009 first edition and includes coverage of Java 6 and Python 2.7 support, multithreading, asynchronous service APIs, and using frameworks such as webapp2 and Django 1.3. (“App Engine does not yet support Python 3,” Sanderson notes.)

The 509-page, 20-chapter book shows how “to develop applications that run on Google App Engine, and how to get the most out of the scalable model. A significant portion of the book discusses the App Engine scalable datastore, which does not behave like the relational databases that have been a staple of web development for the past decade,” the author states.

Sanderson is a technical writer and software engineer at Google, Inc. His new edition is well-written and appropriately illustrated with code samples, diagrams, screen shots and other graphics.

With clear steps and good detail, the book shows you first how to install and use the Python or Java SDKs on Mac OS X, Linux, and Windows machines and how to develop simple Python and Java applications. From there, it expands deeper into the how-to aspects of programming the Google App Engine.

In some chapters, the Python and Java options are presented together. Python’s and Java’s data modeling libraries, however, are discussed in separate chapters.

“Google App Engine, Google’s application hosting service, does more than just provide access to hardware,” Sanderson points out.

“It provides a model for building applications that grow automatically. App Engine runs your application so that each user to accesses it gets the same experience as every other user, whether there are dozens of simultaneous users or thousands. The application uses the same large-scale services that power Google’s applications for data storage and retrieval, caching, and network access. App Engine takes care of the tasks of large-scale computing, such as load balancing, data replication, and fault tolerance, automatically.”

Programming Google App Engine, 2nd Edition can take you from asking “What is Google App Engine?” to well down the road toward becoming an App Engine expert.

Si Dunn

For more information: paperbackKindle