Re: [NTG-context] lpdf.checkedkey has problem with false values

15 Sep 2014


      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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