johnk's blog

Semantics

So I'm reading this computer stuff, and come across:

"What separates a mixin from multiple inheritance? Is it just a matter of semantics?"

"Yes. The difference between a mixin and standard multiple inheritance is just a matter of semantics;"

What the heck did that mean? Different words, same meaning... or different words, different meaning? I am pretty sure they meant the former, but I had to double check, because "semantic" means "meaning", and in technical reading, I tend toward the literal interpretation over traditional or colloquial one.

Craiglist Free Stuff

materials/minerals
	dirt
	rocks
	manure/fertilizer
	metal
	bricks
	broken concrete	
wood
	firewood
	hardwoods
	living trees
furniture
	sofa
	computer desk
	entertainment center
	chairs
	table
	bookshelves
boxes
toys
food
clothes
books/magazines/video
electronics
	television
	computer stuff
	phone
	ewaste
big batches
	curb alerts
	all the stuff in my storage

Operations on a Remote MySQL Server

A demo of how to incorporate SSH tunnels into a Python system administration script.

Like all sysadmins, I write scripts to automate routine operations. Lately, though, I have needed to write scripts that automate routine operations on a remote system, and we need the security barriers to be a little higher than in the "old days".

We're accessing our database through an SSH tunnel, rather than via a regular encrypted socket. (The SSH connection will eventually require key pairs, and disallow regular passwords.)

WSGI, PSGI, Rack - learning some new backend stuff

(This is one of those articles I sometimes fear writing, because it reveals a vast gap in my knowledge. I've spend most of the past decade in PHP programming, with numerous forays into other langauges and frameworks, but mostly in the app dev end. I have to deploy my code and that's made me take forays lower into the stack.)

Two Big Monitors, Justified

I was never one to think I *needed* two monitors after the HD monitors came out, but having used two for a couple months, I think it's totally worth it. I don't even have the second monitor on all the time, but when you're coding and testing interactively, it helps a lot.

I set it up to show four regions: editing, reference, interaction, and debugging. I keep a terminal underneath the editing window, too. Click the image to enlarge.

Python str.split, annoying design.

Even after a year of diddling, I'm still a python newb, and things like str.split(None) are why.

Everyone knows split splits strings on a character (or in the civilized world, a regex). str.split(None) splits on whitespace and then trims leading and trailing whitespace. It's a great feature, but why not call it str.split_whitespace?

'a b'.split(None) returns ['a','b'].

'a,,,b'.split(',') does not return ['a','b']. It returns ['a','','','b'].

Los Angeles Rent Increases

I just got a rent increase, and the text of the letter is pretty unclear about when the rent increase goes into effect. I got the notice around the 20th, so the California law says I need 35 days notice by mail, or 30 days notice in person.

CA department of consumer affairs, rent increases.

Angular JS Doesn't Suck

So I read this somewhat legendary rant about how JQuery is better than AngularJS, and AngularJS will fail. It's not going to fail.

It's just hard to learn. It's also verbose. You could say the same about any of the OO descendents of C. The difficulty generally comes from learning where your code should reside in the framework. Verbosity is just part of writing larger programs, and Angular is about writing larger programs. Maybe not large programs, but larger than a thousand lines.

Security Logic

Came up with this comment to help me think through end-user security.


	/*
	 * Security logic is based roughly on NTFS style allow and deny.
	 *
	 * The logic is as follows, in order:
	 * 1. If a specific role or user is in the deny list, they are denied.
	 * 2. If a specific role or user is in the allow list, they are allowed.
	 * 3. Otherwise, they are denied.
	 *
	 * There are three special values.  Anonymous is a user who is not logged in.
	 * All refers to all roles and users.
	 * None refers to no roles and no users.
	 *

Working at Night is Kind of Lame

So, after writing the big promotional article justifying TDD, I was doing some more Angular programming, and totally not having an easy time writing tests, so I gave up. The dependency injection framework makes it kind of hard. It'll make sense, eventually.

Test Driven Development (a cynical view)

So I'm trying to encourage a coding friend to do some unit testing. According to this blogger, testing isn't so popular in ObjC. Yeah, I can understand. It's a pain in the butt to learn the testing framework, and it's also a pain to write tests.

Then there's the intellectual conundrum: how do you write a good test suite that's likely to find your programming errors?

That's the kind of thinking that will send you down the rabbit-hole of computer (pseudo)science. The short answer is: you cannot. Stop contemplating.

Don't even try.

Change Control Form

This is the change control form that I use, more or less. Less, mainly. I'll use it for major changes, but usually forget about it for smaller ones, which isn't a good thing. Still, in my experience, something is better than nothing.

For a one-person operation, it's OK. Also, if you're doing outside jobs, you do need to document changes in a notebook of some kind, because you won't remember what you did when you return to the site. I forgot to record info about a few remote sites we set up for other organizations - and wasted a couple hours here and there for it.

My Second Angular Directive - Menus

This was downright difficult. The good news is that the code got a little shorter, the HTML is a LOT shorter, the menu settings are in a shorter config file, and the direct manipulation of the DOM has reduced significantly.

When the user clicks on a menu item, here's what happened:

The original scanned the DOM to toggle off the current item. Then toggled the new item.

Now, the new version maintains a copy of the menu configuration, and alters this model. A loop scans the model and sets a "selected" bit, then triggers the animations.

My First AngularJS Directive: Stretchdown - stretches an element to the bottom of the window.

I've made may first directive! OK, not that special, but to me it is. This is one of the more difficult features I've come across in Angular, and I still don't really "get it".

I'm not even going to do a code walkthrough, because I can't really explain it well. The easy part is calculating the height the element should be. The tricky part is implementation.

Chrome Rendering Glitch with Label's Padding in Points (PT), Even Values

I have to learn the Chromium bug reporting system. Found an interesting rendering bug if, on a label, you specify a padding with an even number of points (pt), the rendering is shifted up a little bit, and the border can disappear if it's adjacent to another element.

Two examples are attached, differing only in the amount of padding.

Maybe it's a difference in how the values are calculated and either rounded off or truncated.

The problem goes away if you use pixels instead of points.

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