[Edu-sig] quantum instance

Dethe Elza delza at livingcode.org
Mon Sep 19 23:26:12 CEST 2005

On 19-Sep-05, at 9:26 AM, Kirby Urner wrote:

> We saw how that works in VPython (C++/color), how it works in a  
> triangle,
> how it might work in any number of not-that-unusual circumstances.

I thought I had written an example using PyGame, but I don't see it  
now.  Perhaps it was when I was having trouble with my mail last month.

In any case, one more usecase for properties, related to Kirby's  
triangle example, is PyGame's Rect.  A Rect has the following  
properties, all modifiable, and setting any of them will update any  
related properties:

* top
* bottom
* left
* right
* topleft
* topright
* bottomleft
* bottomright
* midleft
* midright
* midtop
* midbottom
* center
* centerx
* centery
* size
* width
* height

Certainly these are merely conveniences which could be replaced with  
just left,top,width,height (or various other combinations).  However,  
in a game you are likely to need a substantial subset of these in the  
course of the game, and having easy accessors like
this makes the code vastly more readable than strewing

if (sprite.left + sprite.width) > some_offset:

when what you mean is

if sprite.right > some_offset:

For what it's worth


A good engineer is a person who makes a design that works with as few  
original ideas as possible. --Freeman Dyson

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