On Programming

The pattern I've been focused on for some time is the classic 'students in classes' or 'passengers on flights' problem. The database has a table of students and a table of classes and an association table which joins them. That's basic stuff. The problem is how do you update a student to edit her list of classes, or update a class to edit its list of students? The relational integrity is not a problem--if you delete a class from the student, that student no longer appears in the class' list of students. The problem is your simple form gets very complicated. Instead of a form that displays the columns of a single row in a table, now we have three tables involved. Of course it's solvable, but we want it to be intuitive for the end user. Old time software punted the problem--you could edit the association table, or a class, or a student, but you couldn't add classes to a student. What we want is a list of classes on the student record. Each class ...

Fooling around with Bootstrap , which uses jQuery , I realized that enough has changed with the underlying JavaScript that I needed a refresher course. I came across Tokenizer by Don McCurdy , and it uses constructs that I didn't recognize. My copy of JavaScript, the Definitive Guide , by David Flanagan, covers JS 1.5. 17 years later, we're up to ECMAScript 2018--there have been a lot of changes since I worked with Brendan Eich at Netscape. I wanted to come to an understanding of ES6 (2015) at least, and I came across JavaScript: Moving to ES2015 by Ved Antani, Simon Timms, and Narayan Prusty (Packt, 2017) as a free e-book from the Seattle Public Library. The Tokenizer code is less than 300 lines, and much of it is comprehensible, but I ran into this: a = a || func('arg'); This is the hip, trendy way of writing: if (!a) a = func('arg'); Because JS doesn't evaluate the second expression if the first is true. I suppose you could also write ...