Cant set table values with a function?
How can I change table value 2 with a function? When I print the difference it works, but when I print it after it's still 0.
-----global value------
tabledifference= {0,0,0}
function differences(new,current,difference)
difference = new-current
print(difference)
end
print(tabledifference[2])
differences(tableonenew[2], tablecurrent[2], tabledifference[2])
--lets say tabeonenew[2] is 5, and tablecurrent[2] is 50
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2 answers
I'm not 100% sure on what you're asking, but I'll give it my best shot. So, if you're asking how to set the value of a table through a function, you could do it like this:
local tab = {};
setmetatable(tab,{__call = function(self,v,i) local i = i or #self+1 rawset(self,i,v) end});
Now, to add to the table, you can do this:
tab(24,1); -- sets index 1 to value 24
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When you write
differences(tableonenew[2], tablecurrent[2], tabledifference[2])
Lua has to evaluate the arguments. That means it says, "Oh, tableonenew[2] is 5, and tablecurrent[2] is 9 and tabledifference[2] is 4 so let's give differences 5, 9, 4:
differences( 5, 9, 4)
That is, when it's evaluated, you've completely obliterated where it came from -- it doesn't care that you passed it things that were from particular tables.
Instead, you have to pass the tables themselves to allow them to be changed.
-- to = a - b
function differences(a, b, to)
for i = 1, #a do
to[i] = a[i] - b[i]
end
end
Is an example of something that would subtract each element of b from each element of a and store them in to.
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