Re: avoiding recursion in a dump_table function

[Peter Cawley <lua@...>]

On Tue, May 10, 2011 at 4:31 PM, Dave Collins
<Dave.Collins@mercatustechnologies.com> wrote:
> I’ve got a large object which, for convenience of pulling data from it, is
> self-referencing. (sometimes I need items from a dept, sometimes I need all
> items).
>
>
>
> Essentially, I’ve got this:
>
>
>
> Flyer
>
>                 Departments
>
>                                 Dept1
>
>                                                 Item1
>
>                                                 Item2
>
>                                 Dept2
>
>                                                 Item3
>
>                                                 Item4
>
>                 Items
>
>                                 Item1
>
>                                 Item2
>
>                                 Item3
>
>                                 Item4
>
>
>
>
>
> When I need to look inside this table using the following dump_table method,
> I get infinite recursion.
>
>
>
> Any ideas on how I can add some smarts to my dump_table to defeat the
> infinite recursion?
>
>
>
> function dump_table(t, prefix)
>
>       if(prefix == nil) then
>
>             prefix = ""
>
>       end
>
>
>
>       local k,v
>
>       for k,v in pairs(t) do
>
>             if(type(v) == "table") then
>
>                   dump_table(v, prefix .. k .. ":")
>
>             else
>
>                   print(prefix .. k .. "=" .. tostring(v))
>
>             end
>
>       end
>
> end
>
>
>
>
>
>
>
> Dave Collins
>
> Front-End Engineer
>
> Mercatus Technologies Inc.
> 60 Adelaide Street East, Suite 700
> Toronto ON M5C 3E4
> T  416 603 3406 x 298
> F  416 603 1790
>
>
>
> dave.collins@mercatustechnologies.com
>
> www.mercatustechnologies.com
>
>

function dump_table(t, prefix, seen)
      prefix = prefix or ""
      seen = seen or {}
      if seen[t] then
          print(prefix .. " is recursive")
      else
          seen[t] = t
          local k,v
          for k,v in pairs(t) do
                if(type(v) == "table") then
                      dump_table(v, prefix .. k .. ":",seen)
                else
                      print(prefix .. k .. "=" .. tostring(v))
                end
          end
      end
end