February 2009

I use TextMate for work. It’s a good editor, doesn’t get in my way, and I take advantage of relatively few of its nifty features.

One problem with TextMate is that its built-in search is very slow, especially across a large project. Since I work with a full checkout of the deviantART source code, searches can take a while.

So I started using Ack in Project, a TextMate bundle that uses ack to search your project. (Ack is a nifty little tool that combines grep and find, along with a number of useful optimizations for searching checked-out source code.)

However, Ack in Project doesn’t expose a very useful part of ack’s functionality, which is the ability to search just particular filetypes. This has occasionally been a pain – some words appear commonly in PHP and JS files, but I only care about them in the PHP.

So I spent a little while this evening adjusting Ack in Project to let you choose a file type to search.

My Ack in Project tweak

My version is up on github.

If you’d like to use it, do this:

$ cd ~/Library/Application\ Support/TextMate/Bundles
$ git clone git://github.com/kemayo/ack-tmbundle.git Ack.tmbundle

1 2	$ cd ~/Library/Application\ Support/TextMate/Bundles $ git clone git://github.com/kemayo/ack-tmbundle.git Ack.tmbundle

(It was my first time messing with tm_dialog, so I’m not necessarily confident about how I did it. But it works!)

I warn you in advance that this post does not end with a resolution of my problems.

For reasons relating to dynamic loading of javascript dependencies, I wanted to find a way to tell:

When a script tag finishes loading a file
Whether that file was successfully loaded

For various reasons, I didn’t want to add cruft into the files being loaded — no appending a function call to the end of every file, or anything.

Now, the finishes-loading case turns out to be pretty easy, albeit with some quirky cross-browser ramifications:

var eax, load;
eax = document.createElement('script');
eax.setAttribute('type', 'text/javascript');
eax.setAttribute('src', src);
load = function(e) {
    // FF/Safari get the `load` handler, IE gets the `readystatechange` handler.
    // IE doesn't fire 'load' for JS (but does for CSS...)
    if(!eax.readyState || eax.readyState == 'complete' || eax.readyState == 'loaded') {
        // IE6 stalls at 'loaded' sometimes
        alert('loaded!');
        // remove these listeners for everyone, because it's
        // easier than testing everything to find out whether it's needed.
        removeEventListener(eax, 'readystatechange', arguments.callee);
        removeEventListener(eax, 'load', arguments.callee);
    }
};
addEventListener(eax, 'load', load); // FF/Safari get this
addEventListener(eax, 'readystatechange', load); // IE gets this

var eax, load;

eax = document.createElement('script');

eax.setAttribute('type', 'text/javascript');

eax.setAttribute('src', src);

load = function(e) {

// FF/Safari get the `load` handler, IE gets the `readystatechange` handler.

// IE doesn't fire 'load' for JS (but does for CSS...)

if(!eax.readyState || eax.readyState == 'complete' || eax.readyState == 'loaded') {

// IE6 stalls at 'loaded' sometimes

alert('loaded!');

// remove these listeners for everyone, because it's

// easier than testing everything to find out whether it's needed.

removeEventListener(eax, 'readystatechange', arguments.callee);

removeEventListener(eax, 'load', arguments.callee);

}

};

addEventListener(eax, 'load', load); // FF/Safari get this

addEventListener(eax, 'readystatechange', load); // IE gets this

It’s a horrible mish-mash of events, obviously, but it works. Insofar as it goes.

Working out whether the load was successful turns out to be the hard part.

In Firefox it’s very easy. The load event doesn’t fire if there are problems loading the JS file, and a error event fires instead. This is lovely.

In Safari the load event doesn’t fire if there are problems, but there’s no other sign given. So I could probably fake this with a setTimeout set to a reasonable length — not perfect, but good enough for most cases.

In IE the readystatechange event fires away regardless. It’s here that I’m stuck — I can’t see any way to tell, in the readystatechange handler whether the script tag was really loaded without problems.

Since IE represents an unfortunately large component of deviantART’s users, half-working failure detection isn’t going to cut it. Especially since all the developers mainly use Firefox/Safari, and wouldn’t expect IE to behave differently.

So for now I’m going with verifying that the script tag loaded something, and says it’s complete. I’ll keep my eyes out for a way to work around IE…

TextMate bundle: Ack in Project (improved)

Detecting failure

Engagingly quirky