Compare and Merge Apps

You can compare two apps and merge changes between one file and another using the Comparison Tool. The Comparison Tool highlights differences in the code of two apps.

Select Files to Compare

There are multiple ways to select two files and start the Comparison Tool:

• App Designer — Go to the Designer or Editor tab and, in the File section, click Compare To. The Comparison Tool includes the currently open file in the First file or folder field. Click the button to select a second item to compare, or drag and drop a file from your file browser into the Second file or folder field.

• Current Folder browser — Select a file, right-click, and select Compare Against. Click the button to select a second item to compare, or drag and drop a file from your file browser into the Second file or folder field. To select two files or subfolders to compare, Ctrl-click the file names. Then right-click and select Compare Selected Files/Folders.

• Command Window — Use the visdiff function. For example, to compare the two files ExplorerE.mlapp and ExplorerF.mlapp using the visdiff function and the default text comparison, type visdiff('ExplorerE.mlapp','ExplorerF.mlapp'). MATLAB^® opens the Comparison Tool and displays the resulting comparison report.

Explore Differences

When you perform an app comparison, a new window opens and displays the two files side by side. For example, suppose that you have two files ExplorerE.mlapp and ExplorerF.mlapp with several differences. When you compare the two files, the Comparison Tool displays the resulting report.

When comparing apps, the Comparison Tool attempts to match lines and detects code that is added, deleted, or changed. The Comparison Tool displays the total number of differences in the bottom-right corner of the comparison report and highlights the lines that do not match using the colors listed in this table.

Highlight Color	Description
Purple	The line contains differences.
Dark Purple	The highlighted characters are different.
Blue	The line exists only in the right file. This can happen when the line is inserted in the right file, or when it is deleted from the left file. The corresponding line in the left file is highlighted using a gray striped pattern.
Yellow	The line exists only in the left file. This can happen when the line is inserted in the left file, or when it is deleted from the right file. The corresponding line in the right file is highlighted using a gray striped pattern.

To step through the results one difference at a time, use the Next and Previous buttons.

For information about how to configure the comparison report, see Compare Files and Folders and Merge Files.

Merge Changes

When comparing apps, you can merge changes from one app to the other. Merging changes can be useful when resolving conflicts between different versions of an app.

To begin merging, on the Comparison tab, click the Merge Mode button. Then, to replace content from the right pane with content from the left pane, click the button located next to the line you want to merge. You also can select a difference and, in the Comparison tab, click the Replace Content button.

The right pane contains the merged result. An asterisk next to the merged file name in the right pane (ExplorerF.mlapp*) indicates that the file contains unsaved changes.

To undo a replacement, click the Undo button between the modified lines or on the Comparison tab. To revert all merges and start again, click the Refresh button. You also can click the Refresh button to update the comparison report after making changes to and saving the files in the Live Editor. Refreshing discards all merged changes.

To save your changes and return to the comparison report, click the Save Result button. To return to the comparison report without saving changes, click the Return to Comparison button.

Tips for Successful Merging

You can merge changes only in editable code. Sections of code with a white background are editable. Examples of editable sections include the body of functions that you define (such as callbacks and helper functions) and the definitions of custom properties. Sections with a gray background contain non-editable generated code and therefore cannot be merged. If a change spans both an editable and a non-editable section, you cannot merge it.

You can merge changes only from left to right. This makes the order of the files in the Comparison Tool important.

If neither app contains changes in the generated code, place the file containing the changes that you want to merge in the left pane. You can merge only from left to right. To swap a file from the left pane to the right pane, click the Swap Sides button before you start merging. Clicking the Swap Sides button reverts any merges already made and creates a new comparison report for the original files.

If one of the apps contains changes in the generated code, place the file containing the generated code that you want in the merged result in the right pane of the Comparison Tool. To swap a file from the left pane to the right pane, click the Swap Sides button before you start merging.

If both apps contain changes in the generated code, those lines of code cannot be merged in the Comparison Tool. To merge the files, use App Designer to interactively apply the desired changes to the app