Wednesday, November 8, 2017

If you can't find a disc, it ain't where you're looking

There's a disc golf adage that goes "If you can't find a disc*, it ain't where you're looking." I sometimes quote that to students who can't find a bug—they're often convinced that a bug lies in code that is in fact correct. I saw an interesting case of that just now with a Python function I wrote:
def precedes(w1, w2):
    if w1.count() > w2.count():
        return True
    elif w1.count() < w2.count():
        return False
    elif w1.word() < w2.word():
        return False

precedes(w1,w2) should return True if w1 (a word) has a count that's greater than w2. Ties are resolved in favor of the word that is lexicograhically less.

I found that tie resolution wasn't working. I convinced myself that I must have gotten a w1 / w2 reversed, or a conditional operator backwards. I looked and looked at those three comparisons but just couldn't find anything wrong with them.

*Golf discs are about 8.5" in diameter and are often made of bright-colored plastic.

Tuesday, January 31, 2017

Google from the command line

It occurred to me that for Google searches where I don't need suggestions I can do a search by hitting a URL from the command line with this one-line shell script:

% cat gg

Let's make one for Wikipedia, too:

% cat wk

Yup, I should generalize those to a script that looks at its name and maps that to an appropriate URL. Here it is:

% cat hitit
which=$(basename $0)
case $which in

open "$url"

Let's add a couple of symlinks in my sbin directory:

$ ln -s hitit gg
$ ln -s hitit wk

Now, instead of

  1. Switch to Chrome (I use cmd-, 3 with Keyboard Maestro)
  2. Type cmd-L to get to the address field
  3. Type the search string, or use a Chrome "search engine" like w to hit Wikipedia.
I can do this:
% gg astroboy
% wk ruby lang

The above use open(1) on OS X but on Cygwin, which I may be moving back to, I'd hit URLs from the command line with this script:

% cat ffx
"/c/Program Files/Mozilla Firefox/firefox.exe" $*

Sunday, January 29, 2017

uniq(1) -- not just for sorted input

For years I've mostly used uniq -c with sorted input but I've recently realized that uniq is great for vertical compression/counting.

Here I pipe clipboard contents into uniq -c to see how many blank lines appear between the application of changes 6881 and 6882:

 % cb | uniq -c
      1 applying 6881, event id = 148047427, INSERT_TEXT,6239,0,6240,0,[
      1 ]
      1 applying 6882, event id = 148047428, INSERT_LINES,6240,0,7479,0,[
      1 ]
      1 applying 6883, event id = 148047429, INSERT_TEXT,7479,0,7480,0,[
      1 ]
      1 2017-01-29 17:25:00,762 LimitedEditCodeServiceImpl WARN  - Exception applying deltas to program text
      1 java.lang.IndexOutOfBoundsException: Index: 7479, Size: 6244
      1         at java.util.ArrayList.rangeCheck(
      1         at java.util.ArrayList.get(
      1         at
      1         at
      1         at edu.arizona.cs.practice.codeextraction.LimitedEditCodeServiceImpl.doLoadCurrentText(
      1         at edu.arizona.cs.practice.codeextraction.Test1.main(

Below I use uniq -c to collapse repeated lines in query output:

% cb | uniq -c
      1 +----------+---------------------+-----------------+------+
      1 | username | date                | testname        | type |
      1 +----------+---------------------+-----------------+------+
      1 | zjones   | 2017-01-19 09:22:56 | number2letter   |    2 |
      1 | zjones   | 2017-01-19 09:22:56 | number2letter   |    0 |
      2 | zjones   | 2017-01-19 09:23:16 | number2letter   |    0 |
      1 | zjones   | 2017-01-19 09:25:06 | number2letter   |    0 |
      2 | zjones   | 2017-01-19 09:25:08 | number2letter   |    0 |
      1 | zjones   | 2017-01-19 09:25:09 | number2letter   |    0 |
      2 | zjones   | 2017-01-19 09:25:10 | number2letter   |    0 |
      3 | zjones   | 2017-01-19 09:25:11 | number2letter   |    0 |
      3 | zjones   | 2017-01-19 09:25:12 | number2letter   |    0 |
      2 | zjones   | 2017-01-19 09:25:18 | number2letter   |    0 |
      1 | zjones   | 2017-01-19 09:25:31 | number2letter   |    0 |

Friday, January 28, 2011

Please consider the environment before printing this email!

Today's irony: Some people have an email signature that includes an image of a recycling symbol and the line "Please consider the environment before printing this email! Thank you" In a case at hand, that image added 3,297 bytes to the message, which had 118 bytes of true content.

I wonder what the worldwide daily total carbon footprint of all those little recycling images is.

Wednesday, October 8, 2008

Old book clarifies Cairngorm

I have to admit that while I'd read a few things about Cairngorm, it still seemed murky to me. The fog cleared when I read chapter 20 in Developing Rich Clients with Macromedia Flex. It's interesting that although the book predates Cairngorm, its description of techniques that Cairngorm later embodied made things click for me.

This book has cleared some other Flex fogbanks for me, too. I think it's truly a gem that's slipping into the sands of time.

Caveat emptor: the book is based on Flex 1.0/1.5, with ActionScript 2.0 -- you'll need do some translation as you read it, and some things simply no longer apply. But I think it's still well worth the money.

Getting Started with Adobe Flex

I hope to make it more presentable when time permits but FWIW, here are some rough notes on some resources to help people get started with Adobe Flex.

Saturday, October 4, 2008

Chick Magnet

While waiting in line at Subway yesterday, an attractive woman noticed the book I was reading and struck up a conversation with me. The book? "Official Rules of the NFL"

I've never gotten that sort of attention with "Java Persistence with Hibernate" or "JUnit in Action", to name two of many.

Among many other things I learned that the ball must a Wilson. Period.