Merging Source Files

7

This chapter explains how to start Merging, load it with files, and save the output file. The chapter is organized into the following sections:

Understanding Merging	page 55
Starting Merging	page 56
Working with Differences	page 57
Merging Automatically	page 59
Saving the Output File	page 60

When you load the two files to be merged, you can also specify a third file from which the two files were created for comparison. When you have specified this ancestor file, Merging marks lines in the descendants that are different from the ancestor and produces a merged file based on all three files.

• Lines common to both input files

• Resolved differences

Click the Merging icon

Choose Tools Merging

Loading Files

1. Choose File Open.

2. In the Directory field, select a working directory.

This is the default directory used to select and save files.

3. In the Left File and Right File fields, select the two files you want to compare.

4. If you are comparing the files against a common ancestor, enter the earlier version of the two files in the Ancestor File field.

An ancestor file is required to use Auto Merge.

5. If you want to specify the name of the output file, enter it in the Output File field.

The name filemerge.out is the default, and is stored in the working directory.

6. Click Open to load the files.

Figure 7-1 illustrates a loaded Merging window. The names of the left file, right file, and output file are displayed above each text pane. In a three-way comparison, the name of the ancestor file is displayed in the window header.

Current, Next, and Previous Difference

Resolved and Remaining Difference

If the Auto Merge feature is on, Merging resolves differences automatically.

Understanding Glyphs

Three Input Files

• If a line is identical in all three files, there is no glyph.

• If a line was added to one or both of the descendants, then a plus sign (+) shows where the line was added, and the line is highlighted.

• If a line is present in the ancestor but was removed from one or both of the descendants, then a minus sign (-) shows where the line was removed, and the line is highlighted and in strikethrough font.

• If a line is in the ancestor but has been edited in one or both of the descendants, then a vertical bar (|) shows where the line was changed, and the characters that differ are highlighted.

Moving Between Differences

Resolving Differences

To accept a difference:

Click the Accept button, or Click the Accept & Next button to accept the difference and move to the next difference.

• If a line has not changed in all three files, it is placed in the output file.

• If a line has changed in one of the descendants, the changed line is placed in the output file. Changes could be the addition or removal of an entire line, or an edit to a line.

• If identical changes have been made to a line in both descendants, the changed line is placed in the output file.

• If a line has been edited in both descendant files so that it is different in all three files, no line is placed in the output file. You must decide how to resolve the difference--either by choosing a line from a descendant, or by editing the merged file by hand.

You can disable Auto Merge by choosing Options Auto Merge. When automatic merging is disabled, the output file contains only the lines that are identical in all three files and relies on you to resolve the differences.

If you do not specify an ancestor file, Merging has no reference with which to compare a difference between the two input files. Consequently, Merging cannot determine which line in a difference is likely to represent the desired change. The result of an auto merge with no ancestor is the same as disabling automatic merging: Merging constructs a merged file using only lines that are identical in both input files and relies on you to resolve differences.

Save the output file by clicking on the Save button or choosing File Save. The name of the output file is the name you specify in the Output File field.

To change the name of the output file while saving, choose Save As and fill in the new file and directory names in the resulting pop-up window, as shown in the following figure.