Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions
Privacy Policy

  




 

 

Version Control with Subversion
Prev Home Next


Version Control with Subversion - Properties

Properties

We've already covered in detail how Subversion stores and retrieves various versions of files and directories in its repository. Whole chapters have been devoted to this most fundamental piece of functionality provided by the tool. And if the versioning support stopped there, Subversion would still be complete from a version control perspective. But it doesn't stop there.

In addition to versioning your directories and files, Subversion provides interfaces for adding, modifying, and removing versioned metadata on each of your versioned directories and files. We refer to this metadata as properties, and they can be thought of as two-column tables that map property names to arbitrary values attached to each item in your working copy. Generally speaking, the names and values of the properties can be whatever you want them to be, with the constraint that the names must be human-readable text. And the best part about these properties is that they, too, are versioned, just like the textual contents of your files. You can modify, commit, and revert property changes as easily as committing textual changes. And you receive other people's property changes as you update your working copy.

In this section, we will examine the utility—both to users of Subversion, and to Subversion itself—of property support. You'll learn about the property-related svn subcommands, and how property modifications affect your normal Subversion workflow. Hopefully, you'll be convinced that Subversion properties can enhance your version control experience.

Why Properties?

Properties can be very useful additions to your working copy. In fact, Subversion itself uses properties to house special information, and as a way to denote that certain special processing might be needed. Likewise, you can use properties for your own purposes. Of course, anything you can do with properties you could also do using regular versioned files, but consider the following example of Subversion property use.

Say you wish to design a website that houses many digital photos, and displays them with captions and a datestamp. Now, your set of photos is constantly changing, so you'd like to have as much of this site automated as possible. These photos can be quite large, so as is common with sites of this nature, you want to provide smaller thumbnail images to your site visitors. You can do this with traditional files. That is, you can have your image123.jpg and an image123-thumbnail.jpg side-by-side in a directory. Or if you want to keep the filenames the same, you might have your thumbnails in a different directory, like thumbnails/image123.jpg. You can also store your captions and datestamps in a similar fashion, again separated from the original image file. Soon, your tree of files is a mess, and grows in multiples with each new photo added to the site.

Now consider the same setup using Subversion's file properties. Imagine having a single image file, image123.jpg, and then properties set on that file named caption, datestamp, and even thumbnail. Now your working copy directory looks much more manageable—in fact, it looks like there are nothing but image files in it. But your automation scripts know better. They know that they can use svn (or better yet, they can use the Subversion language bindings—see the section called “Using Languages Other than C and C++”) to dig out the extra information that your site needs to display without having to read an index file or play path manipulation games.

How (and if) you use Subversion properties is up to you. As we mentioned, Subversion has it own uses for properties, which we'll discuss a little later in this chapter. But first, let's discuss how to manipulate properties using the svn program.


[an error occurred while processing this directive]
Version Control with Subversion
Prev Home Next

 
 
  Published under the terms of the Creative Commons License Design by Interspire