Re: [Possibly Spam] Re: Size of a non numerical indexed table

[Rici Lake <lua@...>]

It sounds to me like what you are trying to do is retain the order of 
key insertion.

The technique I usually use (for tables with string keys) is to insert 
the keys into the table as well:

local mytable = {}
for i = 1, mytable.n do
  local name, info = readInfo(i) -- Note 1
  mytable[i], mytable[name] = name, info
end

This assumes that all the names will be unique, which is not always the 
case. (It would be easy to check, though)

Then you can access by name:  mytable[key]
or by index: mytable[mytable[i]]

You can loop over all the keys in numeric order:

for i, key in ipairs(mytable) do
  local val = mytable[key]
  ...
end

(You could write a custom iterator to do that, if you prefer)

If the keys are repeated (which is common in parsing internet 
protocols) you need something more subtle, but it can be done.

Note 1:
  local name, info
  name, info = readInfo(i)

compiles into (in effect):
  local name, info = nil, nil
  local tmp1, tmp2 = readInfo(i)
  name = tmp1
  info = tmp2
So:
  local name, info = readInfo(i) is a bit faster


On 1-Sep-05, at 6:52 AM, Jose Marin wrote:

> The solution I've found is to have a 'n' field on the
> table, and update it when I insert a new entry on the
> table:
>
> local mytable = { n = 0 }
>
>
> for i = 1, readInfoCount()
>    local name, info
>
>    name, info = readInfo(i)
>
>    mytable[name] = info
>
>    mytable.n = mytable.n + 1
>
> end
>
>
> print(mytable.n)
>
> Will print the number of members of the table,
> alright, but the problem is if I have a field named
> like "n"...
>
> I could use _n, tableSize or other name to keep the
> table size, but I wonder if there is one clever way of
> do this...
>
> Anyway, thank you all for the tips!
>
> Another question is if it's possible to get a table
> field using an index, on a non numerical indexed
> table.
>
> Yes, I could use foreachi ... but there is a direct
> way of do this?
>
>
>
>
>
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