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Yetzederixx
Beginner
Joined: 19 Oct 2010
Posts: 14
Location: Sulphur, LA
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 Posted: Wed Oct 27, 2010 5:31 am
Function Return Values in Lua
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I wrote a function today because I couldn't figure out how %ismember searched through the variables. So I defaulted my lists to alphabetical and adopted a binary search method. It always returned true, well I thought it was, because in the trigger that calls the function the true always sent the true commands. Well after some testing it wasn't the code that was wrong as #echo @FN would echo true/false as appropriate. When you want to return true/false you have to do so by returning 1 or 0 if you are using zScript to test the return value, at least this is how I got it to work.
| Code: |
--Param 1: Name of character to search for
--Param 2: String list to search in
maxE = table.maxn(zs.param(2))
low = 1 --Lua starts it's arrays at 1 not 0
high = maxE
while low < high do
mid = math.floor(low + ((high - low) / 2))
if zs.param(2)[mid] < zs.param(1) then
low = mid + 1
else
high = mid
end
end
if ((low < maxE) and (zs.param(2)[low] == zs.param(1))) then
return 1
else
return 0
end
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Here's a snippit of the zScript that uses the the function
| Code: |
| #switch (@binIsMember(%1, @BlackRobes)) {#cw 96} |
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Zugg
MASTER
Joined: 25 Sep 2000
Posts: 23379
Location: Colorado, USA
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Posted: Wed Oct 27, 2010 4:58 pm
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Yes, functions always need a return result. Are you reporting a problem, or just letting people know?
The %ismember function in zScript will be faster than your Lua function. %ismember does a fast hash-table lookup, which will be faster than a binary search method and is independent of the list sort method. At least in v3.31. You didn't mention what version of CMUD you are using. In the older 2.37 the %ismember was much slower. |
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Yetzederixx
Beginner
Joined: 19 Oct 2010
Posts: 14
Location: Sulphur, LA
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Posted: Wed Oct 27, 2010 8:50 pm
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Initially I had it return true or false, actually it was:
| Code: |
| return ((low < maxE) and (zs.param(2)[low] == zs.param(1))) |
In the zScript would always read it as a return value of true no matter what, even when testing with a known false value. When I would #echo @binIsMember(char, var) it would echo the appropriate respose of true or false. So I guess I'm sort of reporting a bug, or at least something to be aware of.
Reguardless it was still a good exercise in working with Lua, and I got to read a bunch of good helpfiles reguardless, thanks for the input.[/code] |
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Zugg
MASTER
Joined: 25 Sep 2000
Posts: 23379
Location: Colorado, USA
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Posted: Thu Oct 28, 2010 10:49 pm
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Hmm, interesting. The true/false boolean return should have worked too. Looks like maybe an issue with the Lua boolean values not being converted to the zScript 0/1 values. I'll add that to the bug list.
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