Re: A guide to building Lua modules
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- Subject: Re: A guide to building Lua modules
- From: "Pierre Chapuis" <catwell@...>
- Date: 2014年4月14日 22:49:36 +0200
> On Mon, Apr 14, 2014 at 12:43 PM, Enrique Garcia Cota <kikito@gmail.com>
> wrote:
>> Monkeypatching is a tool. It's a bit more error-prone than others, but
>> mostly because it has been around (popularly) less time. There are
>> things
>> that can be done only through it. That alone justifies its existence in
>> my
>> opinion. But also requires strong reminders of the dangers of not using
>> it
>> correctly.
>
>
> just call it "dependency injection" and you'll be cool again :-)
Dependency injection and monkey patching are not the same thing for me.
Dependency injection done right is something I like. In Lua there are
various ways to do it, for instance with the constructor of a "class"
module ("stateless" in Enrique's posts):
-- mod.lua
local M = {}
M.new = function(printer)
return {print = printer}
end
return M
-- main.lua
local M = require "mod"
local x = M.new(print)
x.print(42)
With a "stateful" module, a closure and a setter:
-- mod.lua
local deps = {printer = printer}
local set_printer = function(printer)
deps.printer = printer
end
return {
print = function(...) deps.printer(...) end,
set_printer = set_printer,
}
-- main.lua
local M = require "mod"
M.set_printer(print)
M.print(42)
--
Pierre Chapuis