Think different
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- Subject: Think different
- From: "Soni L." <fakedme@...>
- Date: 2015年8月30日 21:56:13 -0300
Ok so this post is just a way to show the true beauty of Lua: there are
MANY ways to do a thing.
First: Locals.
We technically don't need the local keyword, except that it's nice for
block-level scoping.
Function-level locals can be declared on the function:
function f(l1, l2, l3, ...)
l1, l2, l3, ... = nil
-- Use l1, l2, l3, ... as locals
end
Modules can be done this way too:
return (function(f1, f2, f3, l1, l2, l3, ...)
function f1(...) end
function f2(...) end
function f3(...) end
return {f1 = f1, f2 = f2, f3 = f3}
end)(nil, nil, nil, nil, nil, nil, ...)
Second: The comma operator.
C has the comma operator. We can emulate it with "and" and "or".
x = (x or true) and (y or true) and (z) -- x = z
Or select.
x = select(-1, x, y, (z)) -- x = z
Third: Stacks.
There are 2 ways to do a stack object in Lua: Either you use tables
(PITA), or you use coroutines: (code may or may not be correct - other
examples available online)
local function stackinternals(op, x, ...)
if op == "push" then
local a, b = coroutine.yield()
return stackinternals(a, b, x, ...)
elseif op == "pop" then
local a, b = coroutine.yield(...)
return stackinternals(a, b, select(2, ...))
elseif op == "peek" then
local a, b = coroutine.yield(...)
return stackinternals(a, b, ...)
end
end
function newstack(...)
local co = coroutine.wrap(function(...)
local a, b = coroutine.yield()
return stackinternals(a, b, ...)
end)
co(...)
return co
end
(It's also A LOT faster than a table-based implementation, and if done
in-thread instead of using coroutines it's even faster!)
[etc]
So what are your favorite ways to do something, and why do you like it?
--
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