Vi? On the internet? No, not that one. I just mean vi keybindings, not the rest of vi. And I’ve just written a jQuery plugin to help make this happen.

On the UNIX terminal, many commands use common keyboard shortcuts to navigate screenfuls of text. j/k for down/up, h/l for left/right, and so on. As far as I know, vi was the first program to use these shortcuts. vi is famous for its modal interface, where different keys mean different things depending on what mode you’re in. In text insertion mode, “hjkl” means exactly those letters. But in normal (or visual) mode, they are the keys you use for navigation. Using standard letters instead of the arrow keys could have come about for a number of reasons. Firstly, there’s the issue that different terminals send different key-codes for special keys like the arrow keys. That’s generally been solved these days, but the other reason still remains: By using the whole alphabet as control keys, you get a startling amount of “command bandwidth” - that is, commands in vi generally require much less finger-contortion than pretty much every other text editor.

vi keybindings are useful on the internet for a third (but related) reason - keybinding collisions. We already have meanings for what the arrow keys do (scroll), and trying to use control-key combinations for webpage-specific functionality is fraught with user frustration, confusion and technical issues.

I’ve noticed it already with a bunch of google products, especially since I started using gmail’s online version most of the time now (instead of Mail.app). Gmail and Google reader are the two big ones that I use, but I’m sure there are more. Both use vi-style keyboard navigation, and both are a delight to use with the keyboard. I’d be surprised if bespin lasts long before a vi-mode is added.

I guess many people think only data-heavy, webapps are worth learning keyboard shortcuts for. But the real benefit comes when everything (or at least most things you care about) use the same convenient shortcuts. I was absolutely delighted when I noticed that every issue of The Big Picture allows you to use j/k to jump to successive images - incredibly useful in this case, because page up/down rarely manages to line up to image boundaries. It’s an unobtrusive addition, and it won’t hurt regular users. But for those who do use it, it quickly becomes indispensable.

So what I’d love is for all websites with many conceptual “items” on a page to implement the j/k keybinding as a minimum (with horizontal and inter-page navigation coming later, hopefully). To this end, I have written a jQuery plugin that should make the process fairly trivial, and allow for “active item” decoration via CSS. Click that link for a demo you can try out yourself.

If there’s enough interest, maybe someone could turn it into a community-based firefox extension (a-la AutoPager) that allows users to define the navigation items for websites that haven’t supplied their own (google search would be a handy one).

It’s worth mentioning Vimperator, which brings vi keybindings to firefox’s UI. To clarify, I’m not talking about browser functionality. I’m happy to use the existing controls for a browser, and leave the alphabet keys for use by the web-page. That way there’s no overlap, and webpages can provide contextual navigation controls that are much more powerful than the basic “scroll down 30 pixels” that a browser provides.

Today I was asked if I knew how to make a recursively default dictionary (although not in so many words). What that means is that it’s a dictionary (or hash) which is defaulted to an empty version of itself for every item access. That way, you can throw data into a multi-dimensional dictionary without regard for whether keys already exist, like so:

h["a"]["b"]["c"] = 5

Without having to first initialise h[“a”] and h[“a”][“b”].

A dictionary with a default value of an empty hash sprang to mind, but after trying it out I realised that this only works for one level. Recursion was evidently required.

So, here’s the python solution:

from collections import defaultdict
new_dict = lambda: defaultdict(new_dict)
h = defaultdict(new_dict)

And the ruby, which seems overly noisy:

new_hash = lambda { |hash, key| hash[key] = Hash.new &new_hash }
h = Hash.new(&new_hash)

I had to refer to this today, when I discovered (much to my surprise) that git submodules update does, for the most part, nothing.

You might expect it to update all my git submodules to the latest revision. Nope, I’m supposed to cd into each of those directories myself and run git pull myself.

The only hint that git update will do nothing of use is a single sentence in the help page, which mentions as part of the update command’s summary: “This will make the submodules HEAD be detached”. Which is a fairly unintelligible statement, even to someone who’s been using git for about a year now.

I can’t imagine when you would run git submodule update after the initial checkout - why doesn’t git submodule init just do update’s job (actually fetching the initial content), and then maybe we could have an update that actually pulls updates? I’d even be satisfied to have to use a flag, like --hard, --please or --come-on-old-chap-just-do-it-would-you

I’m pretty new to git’s submodules, and so far they just seem to take far too many manual steps (I don’t understand why they’re not fetched by a clone, for starters). I feel wrong saying so, but I miss svn:externals.

Tell me, how are things in the land of the other DVCS’s?

Update: Looks like my git is outdated, the newest version (1.6) allows a --merge or --rebase flag to update which sounds like it does what I want. Now I just need to sort out my mac’s package management :s

(view link)

OSX has this great feature where if you hold down SHIFT at the same time as using your mouse scroll wheel, it’ll scroll horizontally instead of vertically. If you don’t have a laptop, this is an immensely useful trick. Sadly, I couldn’t find any way to get this to happen on linux.

But now, thanks to some direction from stackoverflow, I finally figured out how to do it myself. The world of X11 input hackery is somewhat twisted and full of projects either abandoned or in disrepair, but I finally stumbled across the right set of tools.

If you’d like to get this (rather excellent) feature in linux, you will need the following:

• Install the packages xbindkeys and xautomation: sudo apt-get install xbindkeys xautomation

• Save the following file as ~/.xbindkeysrc.scm :

    ; bind shift + vertical scroll to horizontal scroll events
    (xbindkey '(shift "b:4") "xte 'mouseclick 6'")
    (xbindkey '(shift "b:5") "xte 'mouseclick 7'")
  

• Use your favourite mechanism to ensure that the xbindkeys command is run at the beginning of your xsession (I added it to ubuntu’s “startup items” preference, but you can surely use init.d if you’re comfortable with that).

Today I’ve put up the first “releaseable” version of autonose. Basically, it analyses your code’s imports, and determines exactly which tests rely on which code. So whenever you change a file, it’ll automatically run the tests that depend on the changed file (be it directly or transitively). Give it a go, and please let me know your feedback.

All you need do is:

$ easy_install autonose
$ cd [project_with_some_tests_in_it]
$ autonose

See the github project page for further information (and a screenshot).

Can anyone tell me why ruby’s instance_variable_set would possibly require the name of a variable to start with an “@”, rather than simply assuming it? It’s a ruddy instance variable, after all…

I can find no decent alternative to python’s setattr in ruby, which surprises me.