Monthly Archives: March 2015

The number one reason to start using git: interactive staging

Git is an excellent tool for collaborative software development in a number of ways. In my opinion, Git’s most valuable feature – which also happens to be one of its most underappreciated – is interactive staging: git add -i and git add -p. If you are a software development who does not use Git, or if you use Git but do not use this feature, you should not write another line of code until you learn it.

When working on a large project, there is no principle more important than that changesets are atomic. Combining more than one distinct change into a commit is highly detrimental to a project’s history. Muddled changesets are hell for future developers on the project, including Future You. The usefulness of log, blame, bisect, and (not to get hyperbolic or anything) version control itself, depends on commits being logically small units.

But, of course, software is not built linearly. You’re writing cool new feature X, but you notice that in order to complete X, you need to fix bug Y. The problem is that you’re already halfway finished with X. You could: generate a diff file, stash/reset your changes, fix Y, commit the fix to Y, reapply the X diff, and continue work on X. This is a pain. Or you could: commit a large changeset that contains X and Y. But this is lousy for the reasons described above. Ideally, you would be able to fix Y, continue with X, and then sort out the changesets just before commit.

This is what Git’s interactive staging lets you do. Start with a clean index. Begin hacking on X. Stumble on Y. Fix Y. Complete X. Then use Git’s stage to commit Y and X separately.

Here’s a real example. (What follows is a pretty basic situation. git add -p is a subset of git add -i, which is full of whiz-bang goodies.) Say I’m working on fixing some poor localization in BuddyPress. While doing so, I notice that some PHPDoc is missing. So I fix both issues, and git diff shows the following:

is1

Now, I know that Changesets Should Be Atomic, so I want to commit the documentation changes separately from the bug fix. So, instead of git commit -a or git add . – which blindly stage all changes – I jump into patch mode with git add -p:

is2

Git has determined what it considers to be the first “hunk” of changes. (Hunks: it takes one to know one.) I’m then asked whether I want to “Stage this hunk”. Normally I’ll just type y or n, but in this case I see that Git hasn’t made the hunks small enough, so I choose s, for “split”:

is3

The hunk is now split into two. The first sub-hunk is the documentation fix. Let’s stage it with y. The second sub-hunk is the code fix, which we’ll skip for now with n. Rinse and repeat with the second big hunk. git status now shows the following:

is4

The “changes ready to be committed” are the documentation fixes. These can be viewed with git diff --cached. The “changes not staged for commit” are the code changes. These can be viewed with git diff. I’m now ready to commit the first set of changes:

is5

(I typed that commit message in my $EDITORvim – which you can’t see in this screenshot.) Then I’ll repeat the routine for the next set of changes, this time staging them all:

is6

Git’s interactive staging is relatively simple, but will completely change the way you work, in ways that will result in meaningful improvements to your projects over time. This is, IMHO, the #1 reason to use Git, and if you’re not using it – because you’re an SVN user, because you didn’t know about it, because your GUI client doesn’t support it – it’s important enough that you ought to think about changing your toolkit.

I miss my camera

It’s been almost a year since I ditched my smartphone. For the most part, it’s been glorious. Like a slow-growing tumor, I’d hardly noticed the damage that years of carrying a smartphone was doing to my lifestyle and my psyche.

The one thing I legitimately miss is the camera. In one sense, I’m glad to buck my generation’s tendency toward hyperselfdocumentation. At the same time, I have kids. I took many hundreds of photos and videos of my first child on my smartphone. I’ve partially compensated for this with the second child by strategically storing cameras in various parts of my apartment, so there’s always one at hand. In the house, this works. But, with the approach of warm weather, I worry once again about the hassle of filling yet another pants pocket with yet another device.

Friends have suggested that I get a smartphone but don’t use the data. But this is like suggesting that I replace my extracted tumor, but this time put it a little further from vital organs.

I feel like I’d be more likely to carry a point-and-shoot camera if they were more svelte. If the iPhone 6 can take such beautiful pictures, why doesn’t someone market a standalone camera with the proportions of a smartphone? The thinnest cameras I’ve seen are double the thickness of even the bulkiest modern phone – way beyond the point of pocketability. Is there a device out there for me?

phpunit-speedtrap and WordPress/BuddyPress automated tests

One of my personal missions over the last six months has been to shave seconds off of the WordPress and BuddyPress automated test suites. (WP’s tests run in under half the time today than in WP 4.0 – and with the addition of nearly 1000 tests. Score!) One of the tools I use to track down problematic tests is John Kary’s excellent phpunit-speedtrap, which adds a listener to each test run, and produces a report of tests whose running time exceeds a configurable threshhold. phpunit-speedtrap is designed to be used as a Composer dependency, but this is not currently convenient or necessary for the purposes of working with WP/BP (for one thing, I’m the only person doing it). Here’s how I’ve rigged it up to run locally:

  1. Grab a copy of the listener class from Github https://github.com/johnkary/phpunit-speedtrap/blob/master/src/JohnKary/PHPUnit/Listener/SpeedTrapListener.php. I chose to remove the PHP namespacing, but you can do as you wish. Save it somewhere – I put it at ~/.speed-trap-listener.php so that I can use it with all projects.
  2. WP and BP ship with a phpunit.xml.dist config file. The .dist extension means that you can run your own phpunit.xml alongside of phpunit.xml.dist – PHPUnit will prefer the non-dist version if available, while WP and BP’s version control config will ignore it. Copy phpunit.xml.dist to phpunit.xml and add the following block:
       
    	<listeners>
    		<listener class="SpeedTrapListener" file="/home/bgorges/.speed-trap-listener.php">
    			<arguments><br />
    				<array><br />
    					<element key="slowThreshold"><br />
    						<integer>250</integer><br />
    					</element><br />
    				</array><br />
    			</arguments>
    		</listener>
    	</listeners>
    

    Change the slowThreshold and filepath to whatever you’d like.
  3. Run phpunit. You’ll see something like this:
    Screenshot_2015-03-07_11-50-30

Keep on shavin’!