ptalk > November 2003

Freeway of Speech

Freeway Blogger records an interesting exercise in freedom of speech:

Another brick in the wall

Wal-Mart has also lulled shoppers into ignoring the difference between the price of something and the cost. Its unending focus on price underscores something that Americans are only starting to realize about globalization: Ever-cheaper prices have consequences. Says Steve Dobbins, president of thread maker Carolina Mills: "We want clean air, clear water, good living conditions, the best health care in the world--yet we aren't willing to pay for anything manufactured under those restrictions."

Fast Company — The Wal-Mart You Don't Know

My Back Pages

Stumbling around in the blogosphere I came across an article about Dylan, the programming language. Brought back fond memories. I still think it’s the coolest O-O language, but I have to program in the language that will pay the bills…

I have one quibble with the author: Dylan did not invent multi-methods. They have been around since Flavors and LOOPS.

My personal favorite feature that Dylan did invent is sealing, or perhaps more appropriately, opening. Dylan’s sealed and open declarations are the key to its balance of flexibility and efficiency. They let the developer of a module declare which classes and methods are permitted to be extended. This declaration allows the compiler to generate much more efficient code for the case where extensibility is not allowed (outside the module), without burdening the programmer with an excess of type and visibility declarations.

Quoting from Dylan Programming:

A C++ compiler could optimize out the dispatching of a virtual function by analyzing the entire scope of the argument on which the virtual function dispatches, proving that argument’s exact class. Unfortunately, that scope is often the entire program, so this optimization often can be performed only by a linker. Even a linker cannot make this optimization when a library is compiled, because the classes of a library can be subclassed by a client. The complexity is compounded for dynamic-link libraries, where there may be multiple clients at once. As a result, this optimization is rarely achieved in C++.

In Dylan, sealed classes, sealed generic functions, and sealed domains explicitly state which generic functions and classes may be extended, and more important, which cannot. The library designer plans in advance exactly what extensibility the library will have. The Dylan compiler can then optimize dispatching on sealed generic functions and classes and within sealed domains with the assurance that no client will violate the assumptions of the optimization. The sealing restrictions against subclassing or changing method applicability are automatically enforced on each client of a Dylan library.

Little Boxes

I sent a friend my vCard, and he wondered if I knew that I could have separate first and middle names. (My vCard lists my first name as P T, not because I have pointy-haired boss or oil baron aspirations, but because…)

I know I can have a middle name, but I found that if I moved the T to my middle name (even if I spelled out Tucker), then I showed up in lots of places as just P Withington, who I am not. This situation happens in most web forms, computer databases, etc., not just vCards.

I refuse to be fit into a little box, so since I cannot tell computers that I prefer my middle name, I have decided to call myself P T Withington, using P T as my first or given name. It's shorter and more convenient. I have had only one website so brain-dead as to tell me that P T was not a valid name (verizonwireless.com, who seem to be completely clueless: I have spent a month trying to use their site, and each time I get one page further and then have to report a bug because their stupid ASP is so broken).

I've had only one person who misunderstood me when I said I was P T Withington — I got a letter from them addressed to Petey Withington ;-).

A Sense of Balance

Why, when I am carrying a full cup of coffee, do I spill less if I don’t look at it; yet, to balance on one leg, I do best if I focus on a fixed spot?