webdevRefinery Forum: Kyek - Viewing Profile - webdevRefinery Forum

AHAHAHAHAHA HOW COOL IS THIS:



One can now, while running Toady, search for third-party mods that aren't on your local machine, download and install said mod from a remote repository, and load that mod into Toady, ALL FROM IRC WITHOUT RESTARTING :D :D :D :D

(And those first few lines are me developing the mod. The search didn't work because I didn't provide a search term. So I fixed that bug, saved it, live-reloaded the mod, and then the exact same command that didn't work before started working.)

Lemon, on 08 June 2013 - 07:20 PM, said:

To be honest, when I decided I wanted this feature and started exploring how to do it, my first approach was to write my own implementation of 'module' and 'require', overriding require() with a call to fs.readFile() and eval'ing what I got back. Then that tiny voice inside my head saying this is so dirty oh my god this is dirty please don't do this it's so frigging dirty got the better of me and I decided to figure out how Node tracked what's already been loaded. Lo and behold, it was in the docs the whole time. Not exactly well-documented, but there nonetheless.

The more I dug, though, it turns out they really strongly recommend against ever modifying the cache, because it can often result in some nasty circular logic. And they're not wrong; so to be safe, you have to design your app structure around ensuring that there's no way a dynamically reloaded module could ever have a dependency on something involved in loading that module, or loading THAT module, or loading... you get the picture. So after banging my head off the wall for a couple hours, I realized that the core issue is that, in Node.js, modules generally require() anything they need. What if they didn't have to? What if each module was passed its dependencies by the parent sometime after it was require()'d, rather than the module loading its own dependencies when it's potentially not safe?

So I tried it. All Toady mods are functions that accept the module manager class and some other dependencies as arguments, and running that function is what returns the actual mod. So you can require() a mod without it ever touching a core dependency, and then pass the mod its main dependencies (rather than the mod finding them itself) whenever they've all been initialized and you're ready to call that function. Now I can willy-nilly delete almost anything from the cache, reload it, and not have an issue. I just call a function called unload() on each module before I drop it out of the cache so that it can detach its event listeners. (I'm still working on a way to hook node's EventEmitter to let my mod manager forcibly drop any mod's listeners without trusting that the author of the mod will do it in unload(). Nothing elegant so far, but I'm determined)

So that was my really long way of saying: This is totally awesome and incredibly useful, **especially** to upgrade applications that hold open long persistent connections like socket.io does. But to pull it off safely, you have to design your entire application around this "dependency push" pattern. Chances are, any existing application won't be compatible with the concept without a rewrite. Damn.

elias, on 23 March 2013 - 07:54 PM, said:

I can do better than explain The API docs for Node's cluster module have a really fantastic example at the top, and then they explain how it works. A lot of it is handled intelligently for you, once you define what the workers should do and what the leader node is responsible for: http://nodejs.org/ap...cluster_cluster

gibbonweb, on 22 March 2013 - 09:41 AM, said:

That works too and isn't terribly different -- the big benefit of this is that you can, for example, scroll the buffer with your mouse wheel instead of unintuitive keystrokes.

callumacrae, on 22 March 2013 - 01:45 AM, said:

Oh I didn't mean it supports Java as a programming language -- I mean PHPStorm (and all the other JetBrains IDEs that are basically subsets of IDEA) is written in Java. So he'd still have to have Java on his computer ;-)