[NTG-context] Re: You can't use '\prevdepth' in restricted horizontal mode

7 Jan 2025


      On 1/7/2025 3:27 PM, Jeong Dal via ntg-context wrote:
...
Dear Hans,
I tested your code.
...
   local tf = { true, false }
   function document.truthTable(a)
       document.MakeHead(a)
…
…
...
       end
       document.MakeFooter()
   end
This part produces the right logical value.
But, the next part doesn’t produce the correct value.
While the value of each variable is printed correctly,
the values of outputs are  all 0.
...
   local tf = { "1", "0" }
   function document.truthTable(a)
       document.MakeHead(a)
       for i,s in ipairs(tf) do
           for j,t in ipairs(tf) do
               for k,u in ipairs(tf) do
                   context.NC()
                   context(s)
                   context.NC()
                   context(t)
                   context.NC()
…
...
              end
           end
       end
       document.MakeFooter()
   end
I think that the logical function “document.logicF()"is not working for 
the array tf={“1”,”0”}.
In python, 1 and 0 are treated as true and false. But, I read that only 
“false” and “nil” are treated as false in Lua, that is,  “0” is also 
treated as true!
I checked it using the following simple code:
\starttext
\startluacode
if 0 then context("True")
else context("False")
end
\stopluacode
\stoptext
The output
The output is “True”.
Ah, i didn't check the function, so how about this:

    local tf = { true, false }
  --local tf = { "1", "0" }

    function document.truthTable(a,f3,f2)
        document.MakeHead(a)
        for i,s in ipairs(tf) do
            for j,t in ipairs(tf) do
                for k,u in ipairs(tf) do
                    context.NC()
                    context(s and "1" or "0")
                 -- context(s)
                    context.NC()
                    context(t and "1" or "0")
                 -- context(t)
                    context.NC()
                    if #a == 3 then
                        break
                    end
                    context(u and "1" or "0")
                 -- context(u)
                    context.NC()
                    context(f3(s,t,u) and "1" or "0")
                    context.NC()
                    context.AR()
                end
                if #a == 3 then
                    context(f2(s,t) and "1" or "0")
                    context.NC()
                    context.AR()
                end
            end
        end
        document.MakeFooter()
    end

and then you can do

\startluacode

    local function logicF3(p,q,r)
        return ((not p or not q) and r) or (p and (q or not r))
     -- return ((p == "0" or q == "0") and r == "1") or (p == "1" and (q 
== "1" or r == "0"))
    end

    local function logicF2(p,q) -- todo
        return true
    end

    document.truthTable (
       { "p", "q", "r", "f(p,q,r)" },
       logicF3, logicF2
    )
\stopluacode

so no need to store in document.logicXX and no need for that function to 
know about "0" and "1" being rendered,

(btw, logicF2 was not defined in the example)

Hans

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                                           Hans Hagen | PRAGMA ADE
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