JDHarper.com

Emacs: Old, but awesome » 0

I’ve discovered something amazing! It’s an old but powerful text editor called Emacs, which has been developed constantly from the early 1970′s to today.

I’m only just begining to learn about it. I had originally ignored it, thinking it was like its complicated sister program, vi. Vi is very confusing for me, because it has an “insertion mode,” which works pretty much like how you’d expect a text editor to work, and a “normal mode” which is completely insane.

Normal mode in vi lets you move the cursor around in different ways: h,j,k, and l move the cursor left, down, up, and right, respectively; w moves to the next word; b moves to the previous word; % moves from one end of a set of parentheses to another, and so on. You can also delete and move text in this mode: yy will remove the current line, for example, and p will place that line at the current cursor postion.

I’m sure it’s useful if you can adapt to having different modes for typing and and editing text, since you’ll never need to move your hands away from the home position on the keyboard. But I found vi too confusing to use, despite several attempts.

Emacs is similar, in that it’s designed to let you do everything efficiently from the keyboard. But Emacs doesn’t use a different mode for its added features; instead, you use keyboard shortcuts. Ctrl-F moves forward one character, while ctrl-b moves backwards one character. Alt-f and alt-b move forward and backword one word. Ctrl-K kills (cuts) everything from the cursor to the end of the line, and so on.

Vi’s biggest problem was that it would get in my way. If you’re in normal mode and start typing a sentence, you’ll do all kinds of strange things to your file. Emacs doesn’t get in my way; it behaves like I expect it to. This means I can learn new tricks piecemeal rather than having to memorize an entire new set of commands all at once.

The other thing I’m liking about Emacs is how easy it is to customize. It was trivially easy to change Ctrl-z from minimizing Emacs to making it undo. Adding markdown support was just a matter of copying a plugin and pasting a bit of code into a text file.

The next thing I’m going to have to explore in Emacs is orgmode, which I find intriguing.

The Apple Store » 0

Today was the opening day for the first Apple store in South Carolina, down at the Haywood Mall in Greenville. So, just for the novelty of it, my dad, brother, sister-in-law, and I went to visit.

It made me hate Apple just a little bit.

First off, I came around the corner from the entrance and see a line in front of the store. The line ends with an Apple employee, so I figure maybe they’re waiting to talk to her or something. When I tried to walk in, I was stopped by a security guard who told me I had to wait in line just to get in to the store. This got under my skin; it’s just a store. It’s just the trademark Apple arrogance that “our store is so special that you have to wait to get in.”

To be fair, that’s supposed to be just for the first day. But the store wasn’t too crowded at this point (about 8:00 PM). There was no reason to make us wait; it was just annoying.

So, bad start. But since we made the trip all the way to Greenville to see this thing, we waited in line for the five minutes. When we get to the head of the line, an employee in one of their professional blue t-shirts comes up and says to Dad something like “Hi, my name is David. Would you like to go shopping with me today?”

Unfortunately, Dad didn’t catch the wording; my sister-in-law did and repeated it to us later. If he had caught it, he would have said something like “No, I’m here to look at computers. I’m not looking for a date.”

So, Dad talks to the employee while my brother and I go poke at all the shiny aluminum and glass. This is the stuff Apple does well; they do make good products. The problem I have with Apple is the way they sell their products. They want to be my friend, while all I want is to buy a shiny metal box from them.

There’s one other thing that they do at the Apple store that makes them borderline evil: In the back of the store, there’s a table, set several feet lower than the other tables, surrounded by bean-bag chairs and topped with big monitors covered in Disney logos. Get the kids while they’re young.

The whole experience left me feeling like a cat rubbed the wrong way. So, ironically, if you like Apple, I recommend staying away from their stores.

Git Along, Little Dogies » 0

I’ve recently begun using Git, which is a pretty spiffy version control system. In case you’re not familiar with the term: A version control system is a piece of software that programmers use to keep track of different versions of the files they are working on.

If you’ve ever had a folder with files in it like “History Project.doc” “History Project–Old.doc” and “History Project–2010-06-02.doc”, you’ve tried to solve the same problem version control solves–you want to be able to make big changes to a file, but you want to be able to go back to the old version just in case something goes pear shaped.

Version control systems automate this process, keeping project directories a lot cleaner. They are also virtually essential for collaborating on software projects, because each change to each file is saved (along with the name of the person who made the change) and is reversible. You can even split a project into multiple branches and merge the branches back together.

The only downside is that version control systems work best with plain text files. I happen to prefer plain text–they’re are small, easily transformed, and readable on every computer with no additional software–but you can’t use text files for everything. Version control still works with more complex file types, but you lose some of the niftier features, like diffs (which show you exactly what changed between one version of a file and another). Still, version control is great for a lot of projects, especially programming, which is all text files anyways.

There’s a great guide to using version control over at Better Explained, which also explains how to use distributed version control systems (like Git). Now that I’ve got a loose grasp on how Git works, I plan to use it for all my programming projects.

30 Days of Python: Days 20-30 » 0

And we’re done! I have created 30 python scripts this month (only three of which were too lame to post). It’s been a lot of fun, and now I feel much more comfortable with using Python.

It’s amazing how easy python is to work with, really. Some of these tasks I expected to be pretty hard, but there are python modules to help you solve just about any problem.

Here are the last 11 scripts:

Day 20: Unpickled the object saved in Day 19.

Day 21: Created and tested a custom exception.

Day 22: One last lame script, sorry.

Day 23: Played a bit with the Twitter API.

Day 24: Parsed a file from the Metafilter Infodump to see who had the most deleted Ask Metafilter questions.

Day 25: Created an Metafilter Data Dump parser that loads most of the data into python classes (excluding comment data, favorites data, and contacts data).

Day 26: Created a script that uses the Google Maps API to determine which of several addresses is closest to a given addresses. (I’m hunting for an apartment.)

Day 27: Revised Day 25 and converted it into a module for easy use in scripts (like this one).

Day 28: Tried out a really easy to use python twitter module.

Day 29: Used python-markdown to convert markdown text into HTML.

Day 30: Revised 29; now it posts a markdown-encoded text file like this one to my blog as a draft using xmlrpclib.

Thanks to all the hard-working folks who make python and python modules available for everyone to use for free.

Review: The Rapture Exposed » 0

You have no doubt heard of the best-selling Left Behind series of Christian novels. These tell the story of people who were left on earth after the Rapture, when Jesus is supposed to come and take all of the Christians off of the earth in the “twinkling of an eye.” This sparks the Apocalypse, the seven-year “Great Tribulation,” in which The Antichrist takes over the world. There is much suffering and death before Jesus returns again to conquer the Antichrist and rule the world.

This story is based on the beliefs of fundamentalist Christianity; these doctrines were explained to me in high school, reinforced in church, and repeated at Bob Jones University where I attended college.

But the more I thought about it, the less sense it made. The “proof texts” for these prophecies are scattered all over the Bible; there isn’t a chapter of the Bible that clearly explains this chronology of first Rapture, then tribulation, then Second Coming. It’s a framework imposed on the Bible; if you read the Bible with no preconceptions, you would probably not come away with this outline of events.

It doesn’t seem to flow naturally from the text of the Bible. If you read the book of Revelation, you’ll find the first three chapters are letters written to exhort various early churches. Then, the rest of the book abruptly shifts into telling the events of the far future, according to the fundamentalist interpretation. This has always struck me as odd; why should such disparate kinds of teaching be in the same book?

Many of the key phrases in fundamentalist eschatology are not found in the Bible–phrases like “the rapture” and “the Antichrist.” (The word antichrist does appear, but it never refers to a supervillian who takes over the world in the last days; it only appears in the books of I and II John and refers to those who believed that Christ never came to earth in the flesh.) If such things are not found explicitly in Scripture, then where do they come from?

On the recommendation of Fred Clark, I started reading The Rapture Exposed: The Message of Hope in the Book of Revelation by Barbara Rossing, looking for an alternative explanation. I recommend reading it if you have any interest in the book of Revelation or in Christian prophecy.

The first three chapters point out the problems with the fundamentalist prophetic framework–both the mistaken interpretations and the social and political consequences of these beliefs. It also explains where this framework came from: It was invented by a preacher named John Darby and propagated by footnotes and headings in the Scofield Reference Bible.

The rest of the book offers an alternative explanation of what The Book of Revelation means. According to Rossing, apocalypses were common at the time Revelations was written–the word apocalypse meaning a story about a visionary journey. A more modern example of an apocalypse would be A Christmas Carol, where Scrooge sees his past, present, and future, and then changes his life based on the warnings he has seen.

Broadly, the book of Revelation is a criticism of Rome and its worship of Victory. John urges his readers to follow Christ’s example of peace, nonviolence, and sacrifice rather than to embrace the seductive but violent and unjust conquest of the Romans.

The judgments–death, famine, earthquakes, pestilence, and the like, the key events of the Left Behind series–are not guaranteed to happen; they are conditional prophecies. Rossing reminds us of the story of Jonah: He prophesied that God would destroy the city of Ninevah in forty days. The people of Ninevah repented, and God relented and had mercy on the city. If we raise the sword against our enemies, then death and violence and all the rest await us; but if we do not, then those judgments will be held back.

Rossing still believes that Jesus will return, but she does not believe that he will return twice–once to evacuate the believers and once to clean up after disaster has ruined the earth. He will not violently conquer the earth in the climactic battle of Armageddon; he has already won the victory through his sacrifice on the cross.

It’s a fascinating book, especially if you’ve never heard any explanation for the Book of Revelation other than the modern fundamentalist prophetic framework. I still have questions; I’d like to find a more in-depth commentary that approaches Revelations from this perspective.

Today’s cool video: Lightning strikes three of the tallest buildings in Chicago at the same time

The imp gave a nervous cough. ‘Good for you!’ it said. ‘You have wisely purchased the Dis-organizer Mk II, the latest in biothaumaturgic design, with a host of useful features and no resemblance whatsoever to the Mk I which you may have inadvertently destroyed by stamping on it heavily!’ it said, adding,

‘This device is provided without warranty of any kind as to reliability, accuracy, existence or otherwise or fitness for any particular purpose and Bioalchemic Products specifically does not warrant, guarantee, imply or make any representations as to its merchantability for any particular purpose and furthermore shall have no liability for or responsibility to you or any other person, entity or deity with respect of any loss or damage whatsoever caused by this device or object or by any attempts to destroy it by hammering it against a wall or dropping it into a deep well or any other means whatsoever and moreover asserts that you indicate your acceptance of this agreement or any other agreement that may be substituted at any time by coming within five miles of the product or observing it through large telescopes or by any other means because you are such an easily cowed moron who will happily accept arrogant and unilateral conditions on a piece of highly priced garbage that you would not dream of accepting on a bag of dog biscuits and is used solely at your own risk.’

-Terry Pratchett, The Truth

30 Days of Python: Days 13-19 » 0

As you may have gathered, a lot of these scripts don’t do too much useful stuff. I’m using them as a teaching tool, trying things. Later, when I need to use one of these techniques, I can look through these scripts and get a brief reminder of how to parse an XML file or use regex in python or whatever.

Day 13: Figured out how to construct XML with ElementTree.

Day 14: Used regex to search a list of presidents for how many used middle initials in their names.

Days 15 and 16: Extremely lame scripts, not uploaded

Day 17: Download today’s transcript of a room in Campfire; not uploaded because on…

Day 18: Updated Day 17′s script to look up user names from the userid’s Campfire provides.

Day 19: Saved an Object using Pickle

Cross Your Fingers » 0

~~I’m updating to WordPress 3.0 in a moment.~~

Looks like it worked. Let me know if you see any irregularities.

30 Days of Python: Days 6-12 » 0

Day 6: Wrote a disemvoweler to teach myself about how to accept command line arguments and how to use those nifty one-line for statements.

Day 7: Wrote a program that reverses the case of a block of text, to teach myself the basics of Python GUI programming using Tkinter.

Day 8: Wrote a Commute Cost Calculator to reinforce Tkinter stuff. Also tried out py2exe: verdict is Pretty Spiffy.

Day 9: Wrote a really basic counter class to make sure I understood how classes work.

Day 10: Wrote a script that converts all the pictures in a directory to 800px high/wide (saving the originals in a separate directory) and uploads these thumbnails to my server via FTP

Day 11: Wrote a script that converts a string to a QR Code (using the Google Charts API).

Day 12: Installed ElementTree and did some extremely basic XML parsing (using this XML file).

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