I will begin taking this for granted immediately. Thanks, Firefox 3.5b4.

It’s too bad I’ve had such a hard time wrapping my head around the programmable completion toolkit, complete and compgen.

Getting There

I have a function that works like cd, but prepends a specific directory. Our web files are stored in /some/dir/webapp, and I want that directory at my fingertips at all times. Here’s the function:

wa() { cd /web/pscpages/webapp/$1 ; }

With this function, wa brings me to webapp; wa project1 brings me to webapp/project1; and so on. I just provide the full sub-path from webapp. Ideally, I would be able to tab-complete directories in webapp.

complete can pull a list of possible completions from a number of sources: “actions” (like files, directories, commands, shell keywords), command output, a wordlist separated by some whitespace, or the output of a bash function, to name a few. What you’ve typed so far (the “current word”) will be used to filter all the possible completions returned by that source. Say you’ve typed “pro” and then hit tab to autocomplete. The returned completions need to match “pro” at the start of the string, meaning you can’t match against absolute paths like /some/dir/webapp/project1.

compgen can be used to generate a list of possible completions. Matches will be output one per line, and can be piped around for transformations just like any other shell command.

Between these two tools, we have everything we need to autocomplete paths starting in a certain directory. Here’s a compgen that gives us directories matching a specified string:

compgen -d /some/dir/webapp/

Sample output:

/some/dir/webapp/.svn
/some/dir/webapp/project1
/some/dir/webapp/templates
/some/dir/webapp/images

We need to trim leading directories so “pro” matches “project1.” We should also append / to the pathnames, since we’re always matching directories:

compgen -S/ -d /some/dir/webapp/ | cut -b 18-

Playing around with compgen’s arguments, we can further filter the completion list by appending to our string, sort of an implied glob. Use /some/dir/webapp/p, and subdirectories starting with “p” will be returned. This is exactly what we want: compgen takes care of all the filtering for us. We have access to a couple special variables to examine the word the user is expanding. For now, it’s enough just to grab ${COMP_WORDS[COMP_CWORD]} and append it to our path.

When completions are generated by a function, they’re passed back to complete by the $COMPREPLY environment variable. Pulling this all together, we can now create our completion function:

_webapp() {
    local cur
    cur=${COMP_WORDS[COMP_CWORD]}
    COMPREPLY=( $( compgen -S/ -d /some/dir/webapp/$cur | cut -b 18- ) )
}

All that’s left is to tell bash to use this function to complete our argument to wa.

complete -o nospace -F _webapp wa

The Fruits

So, that does it. Our original wrapper to cd, combined with our autocomplete functionality, looks like this:

wa() { cd /some/dir/webapp/$1 ; }
_webapp() {
    local cur
    cur=${COMP_WORDS[COMP_CWORD]}
    COMPREPLY=( $( compgen -S/ -d /some/dir/webapp/$cur | cut -b 18- ) )
}
complete -o nospace -F _webapp wa

Voila. Tab completion in a directory that’s not $PWD, and it even works with subdirectories. I hope this makes autocompletion a little clearer for others.

Here’s a small sample of personas. I usually hide some toolbars for Firefox screenshots, but personas tend to look better with a larger canvas.

Hulu’s desktop application has been released.

Widget in Action

1. Open this page in Safari.
2. Right click some whitespace on the page.
3. Select “Open in Dashboard…”
4. Click the ad. The targetting square will expand to fit the ad, leaving the rest of the page dimmed.
5. Click the purple “Add” button at the top right of the page.
6. Wait for June 6.

Note: I’m not making any money from the above ad, I just pulled the generic flash object URL out of an ad on another site.

Update: Having people pull a web clip from the front page of my site was less than ideal, so I’ve moved it off to a more permanent location. New version will stay put.

For a few months now I’ve been salivating over the Palm Pre. A cell phone driven by browser-based apps is extremely appealing: I know HTML, JavaScript, and CSS, so I know how to program applications for the Pre’s webOS. Historically, I’ve liked Palm’s offerings very much: the m125, m500, and T5 were a big part of my day for years.

Pre news is scarce thus far. Periodically developers get a new nugget in the form of a new rough cut or blog post. Rumors continually surface about who is getting prerelease units and what the release timeframe is.

Occasionally I see what the Twitterverse has to say, but, as often happens on the Internet, it’s a jumble of pointless my-phone-could-kick-your-phone’s-ass arguments. Honestly, I don’t care much for the iPhone: as a gadget, it has never held my interest; as competition to the Pre, I think the market is big enough to handle more than one progressive smartphone. I’m not worried Apple will push Palm out of the market, and Apple’s momentum will prevent the Palm from doing the same. The technology (and we, the consumers) can only benefit from the competition between two great companies producing such great wares. There will be a sharing of ideas, and gnashing of teeth, and threats of lawsuits, and when the dust settles both phones will be better for it.

So, Palm, don’t keep us waiting for the Pre. And Apple, bring on the iPhone 3.0.

Then let the melting pot begin anew.

Update: Details about the Palm Pre launch have been released by the Wall Street Journal.

Years ago, Ultrasoft CheckBook was my go-to application for balancing my checking register. I always had my Palm and the application’s UI was superb, and no transaction was left by the wayside. Recently Charlotte and I tried a simple Google Docs spreadsheet; it was functional but featureless, and we fell out of the habit.

A recent search in Delicious brought me to Buxfer almost immediately. I’ll admit I haven’t shopped around, but Buxfer is almost exactly what I would have created had I created my own transaction register. A quick rundown of the killer features:

• Transaction splitting, with an awesome UI that handles the math for you
• Upcoming (and, optionally, recurring) transactions that show up in your dashboard, on your calendar, and can create transactions automatically when they’re due (a godsend for automatic withdrawls)
• Login via OpenID, Facebook, AOL, Google ID, etc. (cool)
• Transactions via Twitter or email (I’m using this to add new debits via SMS)
• API for everything (JSON and XML responses, plus PNG for graphs)
• RSS feed of transactions and alerts
• Free for basic use, with extra features available for $2-3 monthly

Pretty great, so far. The Twitter integration is key for my usage: I use my phone to direct message @bux and the debit is there for cleanup next time I log in. For those with beefier phones, they have two mobile versions: iPhone and Mobile, depending on your capabilities.

I think this is the app I’ve been waiting for.

Screenshots up next. Note that some of these are from the free demo site.