Re: module question: _PACKAGE
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: module question: _PACKAGE
- From: Luis Carvalho <carvalho@...>
- Date: 2007年2月27日 09:36:58 -0500
> It can be used to locate sibling packages easily. Say I have an engine
> called foo, with a foo.math module and a foo.physics module, you can
> access the math module from the physics module through
> require(_PACKAGE..".math"). Example:
>
> -- foo/math.lua
> module(..., package.seeall)
> function poly(coefs, x)
> local fx = 0
> for i,coef in ipairs(coefs) do
> fx = fx + coef * x^i
> end
> end
> --------
> -- foo/physics.lua
> module(..., package.seeall)
> local math = require(_PACKAGE.math)
> function g(x)
> return math.poly({1,2,3}, x)
> end
> --------
A little off the topic, but this is a bit faster (the coeffs are assumed to be
in decreasing power order):
-- foo/math.lua
module(..., package.seeall)
function poly(coefs)
return function(x) -- Horner's evaluation
local fx = 0
for i, coef in ipairs(coefs) do
fx = fx * x + coef
end
return fx
end
end
--------
-- foo/physics.lua
module(..., package.seeall)
local math = require(_PACKAGE.math)
g = math.poly{1,2,3} -- x^2+2*x+3
Cheers,
Luis.
--
A mathematician is a device for turning coffee into theorems.
-- P. Erdos
--
Luis Carvalho
Applied Math PhD Student - Brown University
PGP Key: E820854A <carvalho@dam.brown.edu>