Computer Programming

Yes, a bit specific, but I need to store some links!

Hating on HATEOAS a little bit, thinking about it a lot

I've been thinking about how to enable HATEOAS on this web app, and it is a mind-bender. Django isn't quite up to it - but it does have a key feature of named links and URL generation that seems like a requirement for HATEOAS. To do HATEOAS, links need to be elevated to a higher status in the system.

For one, on the web, links are very different from the way software internals are organized. In software, and also in URLs, we have hierarchies: paths to files, paths to APIs, hierarchies of objects, and nested data structures.

Python Cheatsheet

When I shift languages, I sometimes make cheatsheets to speed up the transition to the new keywords and syntax. There's only so much shelf space in the brain. This is one I made for Python.

Recreate a Dropped Table in Django Migrations

This is a somewhat embarrassing story, but one that's common enough that you can find it online: I dropped a table, and needed to recreate it, and I'm using those (grr) Django migrations.

The right way out of this mistake is to recover from a backup. But let's suppose I didn't have a recent backup of my development database... because I didn't.

Not Hating on HATEOAS

There's been some loving and some hating on HATEOAS (which I don't know how to pronounce), but I'm starting to get it. See: REST Cookbook, Timeless, and PayPal's API.

The core idea is, in addition to the data, you send over some information about the possible URLs you can use as a next step.

Promises, promises (in Javascript)

This is a short explanation of what promises are, and how they work.

You're probably familiar with callbacks, where you pass a function as an argument to another function, like this:

   f( function b() {...});

When f does something, usually taking some time, it runs b.

Promises are just callbacks with a little more structure.

There's a library called Q that's influencing frameworks like Angular. Q's most visible quality is that it uses a differen syntax:

 

Finding anagrams in a list

I was reading quora and came across a post about someone who was rejected from facebook for a sloppy answer. The question was to make a list of words where the anagrams were grouped at the top.

People consoled the guy.

The answer seemed like a unixy thing. It's not that hard, the trick is to create an index for each word, where the index is the word, sorted by letter.

Demo of rotating an element to make a "dial" or "knob" ui element

Here's a little bit of code that shows how to create a "dial" knob that you can control with the mouse. It's entirely in HTML, CSS and Javascript.

It's not hard, but there are a lot of little details to make it look reasonable and not completely goofy. I think it moves a little weird - and it should respond to both x and y axes, but doesn't.

The sum of two sines, with an offset.

Cast any Javascript Value to a Boolean with Double Exclamation

It's a way to cast any variable to a boolean.

var x = true;

!!x === true; // this is a fact

Sometimes, we do a check on an object:

if (window.foo) {
  ...
}

However, if we assign a variable like this:

var isFoo = window.foo;

isFoo will now contain a reference to window.foo. 
If you want isFoo to contain the truthyness of 
window.foo, you do this:

var isFoo = !!window.foo;

Nesting Angular Directives

I've been learning how to write directives, and it's really tough to grok how to do it. This blog post's been rewritten three times so I don't come off as totally ignorant about the "right way" or "the Angular way" to do things.

What I'm trying to do it implement a menu display with lightweight, role-based control over what is displayed.

My first iteration was done entirely with controllers, HTML, and jQuery and plain Javascript. That was clearly not the Angular way, so I revised it a little bit - CSS animations, and let's use directives.

Angular Service and Factory

I was reading the docs, and read things that seemed to contradict what I thought. I thought that Services were singletons, and Factories were instantiating new instances. It turns out that's not quite right. It's explained well here.

Base32 Encoding and Decoding in Javascript

This is a simple implementation of base 32 encoding and decoding that conforms to RFC 4648.

CSS Animations using Transitions with Conditional CSS, Stacked Rectangles

This is a somewhat elaborate example of how to use conditional CSS and transitions to create a fluid, responsive stack of rectangles that are polite enough to stack up when the screen is narrow. The idea is I'm working on is to have a menuing system that stacks when the screen shrinks.

CSS Animations via Transitions

I don't know anything about CSS Transitions, so I made this little demo to try it out. It's ultra-simple, and I normally wouldn't post this kind of thing, but the examples I saw were a lot snazzier, so it was harder to read the code. (To this end, this is probably too fancy.)

CSS Animations via Styles (similar to jQuery animations)

This explores how to do CSS-style based animations, where the animations are controlled via Javascript code that adds and deletes class names from the className property.

Script to Turn IP Camera Uploaded Images into Videos (Unix)

This script combines individual photos into a video, and adds a timestamp to each frame. It's a poor mans security camera video maker.

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