Re: Filtering Iterator
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: Filtering Iterator
- From: Kevin Martin <kev82@...>
- Date: 2012年12月22日 17:05:14 +0000
On 22 Dec 2012, at 16:19, joao lobato wrote:
> However, all that packing and unpacking is bound to have a performance
> hit.
I hadn't considered that, as in almost all cases there is only one return value. I will think about your suggestions, thanks.
On 22 Dec 2012, at 16:34, Dirk Laurie wrote:
> Is there a reason why the obvious Lua code is inefficient, obscure
> or not applicable?
I want to write the following code:
for a in carer:availBlocks() do
--do something with a
end
I do not want to write:
for a in carer:toProblem():availBlocks() do if carer:id() == a:carer():id() then
--do something with a
end
Without an iterator filter, the only way I can think to implement, carer.availBlocks is to use a temporary table:
function carer_mt.availBlocks()
local t = {}
for b in self:toProblem():availBlocks() do
if b:carer():id() == self:id() then
t[b] = true
end
end
return pairs(t)
end
Sometimes there are 1000s of elements and repeatedly creating the temporary table for every time I iterate seems like a bad idea.
Thanks,
Kevin