Re: Making the use of luapgsql more "Lua-ish"

[Marc Balmer <marc@...>]

> Am 23.12.2015 um 16:37 schrieb Jay Carlson <nop@nop.com>:
> 
> On 2015-12-23, at 9:20 AM, Marc Balmer <marc@msys.ch> wrote:
>> 
>> I am currently working on making the Lua PostgreSQL interface more user friendly, more Lua-ish, and I would appreciate comments...
>> 
>> The iterator sets a metatable on the returned tuple to define the __index metamethod for direct field access, so it can be further simplified:
>> 
>> 	p.acct = {}
>> 	for tuple, row in  res:tuples() do
>> 		p.acct[row] = {
>> 			account_nr = tuple.account_nr,
>> 			account = tuple.account,
>> 			class_nr = tuple.class_nr,
>> 			group_nr = tuple.group_nr,
>> 			subgroup_nr = tuple.subgroup_nr,
>> 			class = tuple.class,
>> 			group = tuple.group,
>> 			subgroup = tuple.subgroup
>> 		}
>> 	end
>> 
>> In the last step I added the __call metamethod to result set, to create the nested table structure in one single call
>> 
>> 	p.acct = res()
> 
> Doesn't make much difference, I think. A lot of uses would just use the tuples() like a cursor.
> 
> If row always starts from 1, users can do something like this generic function to get an array:
> 
> function list_from_iterator()
>    local l = {}
>    for v in iterator do
>        l[#l+1] = v
>    end
>    return l
> end
> 
> p.accts = list_from_iterator(res:tuples())
> 
> People seem to treat Lua code as less convenient than C code though....


In our case it is not all about convenience, but we want to have the Lua code as small and concise as possible, because that is sometimes maintained by third parties that are not so Lua proficint,

"exploding" PostgreSQL result set into a nested table structure is about ten lines of C code only, so it's a small addition anyweays.