Re: lpdf.checkedkey has problem with false values

[Hans Hagen <pragma@wxs.nl>]

On 9/15/2014 8:25 PM, Michail Vidiassov wrote:
> Dear Hans,
>
>> well, they're just not treated special
>
> IMHO, they have to be treated special.
>
>> you can try this (untested)
>
> I have tested it. It adds nice enhancement, but does not fix the bug
> In the following case
> local a = {}
> a["e"] = "blabla"
> a["t"] = "true"
> a["f"] = "false"
> a["x"] = true
> a["y"] = false
> a["z"] = nil
>
> your new lpdf.checkedkey correctly fetches "t" and "f", where the old
> one failed.
> And your new lpdf.checkedkey fails for "e" - if I attempt to fetch it
> as boolean I get false instead of nil.
> (That is caused by toboolean returning false for unconvertible data -
> unlike tonumber).
>
> But I did not complain about reading strings!
>
> My problem was with "y".
> Both your new and old lpdf.checkedkey fetch it as nil instead of false.
> My (somewhat ugly) idea of the fix is the following
>
> local function lpdf.checkedkey(t,key,variant)
>      local pn = t and t[key]
>      if pn then
>          local tn = type(pn)
>          if tn == variant then
>              if variant == "string" then
>                  return pn ~= "" and pn or nil
>              elseif variant == "table" then
>                  return next(pn) and pn or nil
>              else
>                  return pn
>              end
>          elseif tn == "string" then
>              if variant == "number" then
>                  return tonumber(pn)
>              elseif variant == "boolean" then
>                   if     pn == "true" then
>                     return true
>                  elseif pn == "false" then
>                     return false
>                  end
>            end
>          end
>      elseif t and t[key] ~= nil and variant == "boolean" and
> type(t[key]) == "boolean" then
>          return t[key]
>      end
> end

more like

function lpdf.checkedkey(t,key,variant)
     local pn = t and t[key]
     if pn ~= nil then
         local tn = type(pn)
         if tn == variant then
             if variant == "string" then
                 return pn ~= "" and pn or nil
             elseif variant == "table" then
                 return next(pn) and pn or nil
             else
                 return pn
             end
         elseif tn == "string" then
             if variant == "number" then
                 return tonumber(pn) -- or nil
             elseif variant == "boolean" then
                 return string.is_boolean(pn,nil,true)
             end
         end
     end
end



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                                           Hans Hagen | PRAGMA ADE
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                                              | www.pragma-pod.nl
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