But there are equivalents for any programming language, but others here have already touched on them.
I'm not sure what SQL has built in, but I'd just use the C preprocessor if I needed that. However, I'd much rather not muck with my queries like that, because that will cause nasty surprises in production.
And I don't eat carbs, so your off the hook for a cake.
This is an interesting idea! What was the problem you were solving that required this?
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I think actually the C preprocessor would solve a lot of the problems that, say, SCSS solves too:
// put these in a header file, 'cssutil.h'
#define HASH #
#define f(x) x
#define COLOR(c) f(HASH)c
#define PREFIXED(x, y) \
-webkit- ## x : y;\
-moz- ## x : y;\
-o- ## x : y;\
x : y
#define SHADOWED PREFIXED(box-shadow, 10px)
// then in your css
#include "cssutil.h"
#define THEME_BG COLOR(fff)
div.main {
background: THEME_BG;
SHADOWED;
}
There we go, pristine(ish) CSS, unsullied by magic constants and messy prefixes! (note that my preprocessor-fu is weak, I don't know how to do variadic prefixes)Different languages have different optimization techniques for removing code during compilation. Java, for example [1], can optimize out based on static boolean variables. I recommend learning more about each individual language and what it offers to get the best out of it.
[1] http://stackoverflow.com/questions/1344270/java-preprocessor
The comment trick isn't useless during development, but I'd see myself using a macro rather than trying to remember just where a slash goes.