Re: Possible bug with the length operator
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- Subject: Re: Possible bug with the length operator
- From: Mason Larobina <mason.larobina@...>
- Date: Tue, 5 Apr 2011 20:00:02 +0800
I have a current usecase in public code which uses a grey area (as far
as I can see) in the current len operator definition.
My code creates holes to truncate items from a list but the len
operator is never called while the table has holes in it.
This is a cut down example of the method:
#!/usr/bin/env lua
-- Items are created or cleared to meet the required new_size
function update(t, new_size)
local tlen = #t -- cache item size
for i=1, math.max(tlen, new_size) do
if i > new_size then
t[i] = nil -- collect item
else
if not t[i] then
t[i] = true -- create item
end
-- do something
end
end
end
local t = {}
for _, new_size in ipairs{10, 1, 100, 60, 30, 65, 8, 64} do
update(t, new_size)
assert(#t == new_size, "size mismatch")
print(#t, new_size)
end
I've never seen an incorrect size returned by #t so far but is this
behaviour subject to change in later lua versions?
Mason