Recipe 6.11 Creating Code Patches

6.11.1 Problem

You need to coordinate your development with another team of developers using a patch they can install to update their code.

6.11.2 Solution

Create a code patch so that they can update their code. (Note that this is a code patch, not a binary patch. Eclipse can use this patch to update source code to match another version.)

6.11.3 Discussion

Say your version of the code displays the text "No problems here.":

public static void main(String[] args)
{
    System.out.println("No problems here.");
}

But the code the other team is using from the CVS repository displays "No problems at all.":

public static void main(String[] args)
{
    System.out.println("No problems at all.");
}

To update the other developers without changing version numbers, you can create a code patch. To create a code patch, Eclipse compares your local code to what's in the repository and creates a patch file holding the differences.

To create a code patch using your local version of a file as the version to which the patch will update the version in the repository, save your file locally, right-click it, and select Team Create Patch, opening the dialog shown in Figure 6-12.

Figure 6-12. Creating a new patch

In this example, we'll save the file named patch in the current workspace, as shown in Figure 6-12. Click the Finish button to save the patch.

This creates the text file named patch. Here's what that file looks like; you can see the line to remove marked with a - and the line to add marked with a +:

Index: GreetingClass.java
===================================================================
RCS file: c:/repository/GreetingApp/org/cookbook/ch06/GreetingClass.java,v
retrieving revision 1.2
diff -u -r1.2 GreetingClass.java
--- GreetingClass.java    25 Feb 2004 16:34:07 -0000    1.2
+++ GreetingClass.java    25 Feb 2004 18:12:18 -0000
@@ -17,6 +17,6 @@
 
 public static void main(String[] args)
 {
-    System.out.println("No problems at all.");
+    System.out.println("No problems here.");
     }
 }

To apply the new patch to code that has not yet been patched, right-click the file to be updated in Eclipse and select Team Apply Patch, opening the dialog shown in Figure 6-13.

Figure 6-13. The Apply Patch dialog

Click Next to open the dialog shown in Figure 6-14. In this dialog you can review the changes the patch will create in the local version of the file. As shown in the figure, Eclipse will change the line:

System.out.println("No problems at all.");

to:

System.out.println("No problems here.");

To apply the patch, click Finish.

Figure 6-14. Accepting a patch

Applying the patch makes this change to the code in the other team's installation of Eclipse, as shown in Figure 6-15. Note that the version number of the file was not changed, but the file was updated with the new code.

Figure 6-15. Applying a code patch