my recent reads..

Tripping up on base64 encoding with webcache

Looking at an Oracle Portal installation recently, I wanted to call the WebCache invalidation API from SQL.

$ORACLE_HOME/webcache/examples/invalidation.sql sounds like a good idea, until:

Error report:
ORA-06502: PL/SQL: numeric or value error
ORA-06512: at "SCOTT.BASE64_ENCODE", line 51
ORA-06512: at "SCOTT.BASE64_ENCODE", line 57
ORA-06512: at "SCOTT.INVALIDATE", line 38
ORA-06512: at line 2

Uh-oh. The base64_encode function included in the script is having trouble with the password. A quick look at the code...
create or replace function base64_encode
p_value in varchar2
return varchar2 is

BASE64_KEY constant varchar2(64) :=
l_buffer varchar2(32767);
l_len integer := trunc(length(p_value) / 3);


for i in 0..l_len loop
l_buffer := l_buffer || encode_chunk(substr(p_value, i * 3 + 1, 3));
end loop;

return l_buffer;
end base64_encode;

Note l_len division by 3, then using it in the for loop. Yep, classic 0/1 base offset issue. Any password with a length of 3, 6, 9 etc characters breaks the code. Fixed with a -1:

for i in 0..l_len - 1 loop
l_buffer := l_buffer || encode_chunk(substr(p_value, i * 3 + 1, 3));
end loop;

But that raises more questions. What is this base64 encoding function doing here anyway?

At some point in time it might have been required, but Oracle Database has had the standard function utl_encode.base64_encode for at least a few versions. It encodes RAW so there's a bit of friggin around with types:
select utl_raw.cast_to_varchar2( utl_encode.base64_encode( utl_raw.cast_to_raw('password1') ) ) as B64 from dual;


I did note the comment in invalidation.sql to the effect that:
-- this old example is replaced by 2 files, collectively known as the
-- PL/SQL invalidation API.
-- the 2 files are
-- wxvutil.sql which does similar things as what invalidate.sql did
-- wxvappl.sql which is a wrapper of wxvutil.sql
-- both files are located in the same directory.

Well, these files are not in the same directory (they are actually in ../toolkit), and what's the excuse for shipping broken examples anyway, even if they are old and obsolete?
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A case of severe backblogarrythmia

My backblog is giving me the irits. And what's worse I join the sad club of people who thought they cleverly invented a new word!

Backblog - Overflow of incidents you intend to write about on your weblog.

However, perhaps I can claim backblogarrythmia as my own:
.. a disruption in the regular flow of weblog posts, often caused by overwork, booze or a new romance. Primary symptom is the backblog, which in turn can exacerbate the problem through increased levels of performance stress. Treatment: JFPS*.

I used to work in a factory where I swear one of the leading hands had a personal goal of inventing a new word everyday. He'd casually call over something like "Hey, pass me the gumlicker would ya?" and take great pleasure in our confusion. He'd be mock-shocked of course at our "ignorance", and delight in explaining the word and how stupid we were for not knowing it. Crazy thing is, he'd always have a great and usually convoluted etymology.

He did this pretty much every day I knew him. Just an average working class bloke, with an average education. But I always secretly admired and envied his creativity with words, wondered where the inspiration came from, and whether he'd use the gift for anything more than keeping his workmates from boredom.

Me? The only words I invent tend to arrive as serendipitous typos. Yesterday's effort:
Museover - particularly thought-provoking and succinct tip or pop-up text that is displayed when you hover your mouse over an icon or word.


Update 27-Jan: It's official: museover and backblogarrythmia are in the (pseudo)dictionary

* just fucking post something
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The Elements of Style (Illustrated)

I raved about Robert W. Harris' When Good People Write Bad Sentences a few weeks ago. Since then I saw Jeff Atwood's post making the point that great coders bring many of the same skills used in writing to their programming. Jeff cited the Strunk & White classic, The Elements of Style.

So I thought may be it's time to check it out again. I have vague memories of seeing it back at school; I certainly don't remember studying it in any concerted way.

I was unsurprised to discover that the core of the book remains a concise litany of rules of correct English usage. Exactly the kind of un-engaging treatment that I praised When Good People Write Bad Sentences for avoiding.

This part of Elements of Style is remains a great reference guide; you wouldn't really want to just read it like a book. It makes me wonder why we don't have these style guidelines built into our word processor and editing software. Sure, we have spelling and grammar. But as these books prove so well, the correct words in the right order does not alone make for good style.

I did, however, read the illustrated Fourth Edition from 2000. It has two surprises that take it beyond a simple reference book.

First, the quirky "American Modern" illustrations by Maira Kalman are a delight to browse.
His first thought on getting out of bed—if he had any thought at all–was to get back in again.
His first thought on getting out of bed—if he had any thought at all–was to get back in again.

Second, we have the new chapters added by E.B. White such as "An Approach to Style". These provide much more interesting reading, with a humorous vein in the same class as "When Good People Write Bad Sentences".
Another segment of society that has constructed a language of its own is business.

Its portentious nouns and verbs invest ordinary events with high adventure, executives walk among toner cartidges, caparisoned like knights. We should tolerate them-every person of spirit wants to ride a white horse. The only question is whether business vocabulary is helpful to ordinary prose. [...]

A good many of the special words of business seem designed more to express the user's dreams than to express a precise meaning.

DeGarmo and Lister had a name for that in Peopleware: Management by Hyperbole!

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Code formatting and line continuations with Javascript and CSS

I've had a question up on stackoverflow recently in an attempt to get a nice solution for adding a glyph with CSS to indicate a wrapped line (e.g. in a command line sample).

With a few good suggestions, I had a reasonable solution but it still required a bit of manual markup to prepare the example. Then I saw Pranav Prakash's post about syntaxhighlighter by Alex Gorbatchev.

With a few tweaks (see the stackoverflow question for the details), I'm now able to combine the best of both worlds: great formatting and syntax highlighting with syntaxhighlighter and also line continuation glyphs. Here's an example of the result:

public class HelloWorld {

public static void main (String[] args)


System.out.println("Hello World! But that's not all I have to say. This line is going to go on for a very long time and I'd like to see it wrapped in the display. Note that the line styling clearly indicates a continuation.");



NB: if you have javascript disabled, or reading this through a newsfeed (or if I hit a bug) you may not see the full effect. Here's a screenshot of what should be appearing above:

Now I just need to go back and update the code formatting in all my old posts. Basket!
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