Wednesday, July 10, 2013

Tutorials need a section on best practices

I took a bit of a break from Effes over the Fourth of July weekend to relax with friends, watch some TV and teach myself node.js by jumping into a small project. The process reminded me of a problem I've hit a few times in various self-learning exercises: docs for languages and frameworks tend to focus almost exclusively on syntax, APIs and other hard facts, but they don't talk much about best practices.

With Node, my question was how to get around the "staircase problem," where indentations march the code off the right side of the screen. Node is non-blocking and uses callbacks for just about anything that goes to the outside world. For instance, its mysql module puts its result set into a callback. That has some neat benefits, it leads to indentation hell. Here's an example in CoffeeScript:

m = mysqlPool()
m.query getFizzes, (err, fizzes) ->
  if err?
    console.log "Error: #{err}
    foos = [ for fizz in fizzes]
    for foo in foos
      do (foo) ->
        m.query selectBars, [foo], (err, bars) ->
          if err?
            console.log "Error 2: #{err}
            console.log("Found a bar!", b) for b in bars

That barely even fit in this blog layout; I had to change bar to b in the last line. And while it's true that blog layouts aren't where most coding happens, the staircase problem is annoying and makes code hard to read.

Now, this is not the biggest problem in the world, but it does make code a bit hard to read if the sequence of actions gets much longer (it's only two above). I solved it in one kinda-hairy section (4-long sequence with a conditional, oh man!) with a bit of refactoring, but the resulting code was actually a bit harder to follow because it broke up the logic's natural flow.

There are other ways I could have solved the problem, and there's at least one third-party module that may help, but here's the real point: the Node docs don't help me out. They don't even acknowledge the problem. If the best thing to do is to use async with CoffeeScript, Node should tell me so.

Maybe it's unfair to pick on Node's docs, since there's barely anything as far as a tutorial. You've got a "hello world" example on the front page, a link to the built-in library's APIs, and that's about it. But it's not just Node.

For instance, the intro guide for Ruby on Rails promises to teach the reader "the basic principles of MVC," but it never mentions MVC again, and doesn't give much guidance for when to put logic in a controller vs a model. Github doesn't talk about the benefits of forking vs branching — the first three hits for "git fork or branch" on google are all on Stack Overflow. Guice's tutorial doesn't tell us where to put our injector. And so on.

I'll give the RoR guide some slack, because MVC has been around for a while; maybe they just assumed that most of their readers would already know it. But in general, the more newfangled a technology is, the more its project should tell newbies not just how to use it, but how to use it well.

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