Why use local variables?

[vrld]

Not sure why no-one mentioned this yet, but local variables are the only way to create closures. A toy example:

Code: Select all

messages = {'hey!', 'listen!'}
closures = {}
for i = 1,10 do
    local m = messages[math.random(#messages)]
    closures[i] = function() print(m) end
end

for _, f in ipairs(closures) do
    f()
end

Or this

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function newCounter()
    local i = 0
    return function(inc)
        i = i + (inc or 1)
        return i
    end
end

a, b = newCounter()
print(a(3)) --> 3
print(a(), b()) --> 4, 1

[seeker14491]

Code: Select all

function newCounter()
    local i = 0
    return function(inc)
        i = i + (inc or 1)
        return i
    end
end

a, b = newCounter()
print(a(3)) --> 3
print(a(), b()) --> 4, 1

b is nil, so that last line would error.

[Roland_Yonaba]

b is nil, so that last line would error.

True. I guess what vrld wanted to mean was:

Code: Select all

    -- same as before ...
    a, b = newCounter(), newCounter()
    -- same as before ...