Re: Avoiding temporary tables
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- Subject: Re: Avoiding temporary tables
- From: Javier Guerra Giraldez <javier@...>
- Date: Sat, 1 Jun 2013 15:13:43 +0000
On Sat, Jun 1, 2013 at 1:01 PM, Luis Carvalho <lexcarvalho@gmail.com> wrote:
> A simple solution is to add a parameter that specifies if you want a copy or
> not:
>
> local _myfunc = myfunc
> myfunc = function (x, copy)
> return _myfunc(copy and copy(x) or x)
> end
what i do sometimes is to add an optional argument for the copy:
myfunc = function (in, dst)
dst = dst or in
.... do all work, reading parameters from in, writing to dst
return dst
end
so, it's used like:
result = myfunc{a,b,c}
-- result is the same table, no allocations
or:
obj = {a,b,c}
myfunc(obj)
-- obj is modified in place
or:
obj = {a,b,c}
result = myfunc(obj, {})
-- result is the new table allocated just before calling
-- obj is not modified
or:
result = myfunc({a,b,c},{d,e})
-- result is a new table, with some 'default' results
--
Javier