A Guide to Using SVN Helper Functions in review

Source: vignettes/svn-helpers.Rmd

This vignette provides detailed documentation and usage examples for two key functions in the review package: svnLog() and svnExport(). These functions simplify interacting with SVN-managed files by retrieving revision histories and restoring previous versions.

Table of Contents

  • svnLog(): Retrieves the edit history of a file
  • svnExport(): Restores a file to a specified revision

svnLog()

The svnLog() function provides the history of all edits made to a file, including the author, revision, and date/time of each commit. This function helps track modifications and identify specific revisions.

Usage

Let’s examine the history of script/data-assembly.R.

Retrieve File History 

svnLog("script/data-assembly.R")

Output:

rev author datetime msg
3 Bob 2025-01-15 10:00:00 Added new feature
2 Alice Johnson 2025-01-10 09:00:00 Modified data load
1 John Smith 2025-01-05 08:30:00 Initial commit

The data frame above shows the commit history, sorted such that the most recent commit appears in the first row. It includes columns for the author, revision number, and commit timestamp. This information is essential for efficiently restoring or reviewing previous versions.

svnExport()

The svnExport() function restores a file to a specified revision, saving it with a new name to avoid overwriting the current version. This is particularly useful when paired with svnLog() to identify the desired revision.

Usage

Restore a Previous Revision

Using the revision numbers from svnLog(), we can restore the first revision of the file:

svnExport(.file = "script/data-assembly.R", .revision = 2)

This creates a new file, data-assembly-2.R, in the repository directory. You can confirm its existence:

file.exists("script/data-assembly-2.R")
TRUE

Summary

By combining svnLog() to identify revision numbers and svnExport() to restore specific versions, you can efficiently manage and review file changes in your SVN repository. The restored files are saved with a new name using the format {original_file_name}-{revision_number} to preserve your working version.