assert on unrecognized directive

saves four tokens and is more diagnostic.

chameleonic.p8

@@ -38,6 +38,39 @@ function cycle(tbl,period)
  return tbl[t()%period*#tbl\period+1]
 end
 
+-- fake sprintf function
+-- %~ for literal "%"
+-- %v for param
+-- %! for tostring(param)
+--    which dumps tables
+function fmt(f, ...)
+ local out, i = "", 0
+ for s in all(split(f,"%")) do
+  if i == 0 then
+   -- before first format directive
+   out ..= s
+   i = 1
+  else
+   local m = s[1]
+   if m == "~" then
+    out ..= "%"
+   else
+    local p = select(i,...)
+    i+=1
+    if m == "v" then
+     out ..= p
+    elseif m == "!" then
+     out ..= tostring(p)
+    else
+     assert(false, tostr(m).."is not a formatting directive")
+    end
+   end
+   out ..=sub(s,2)
+  end
+ end
+ return out
+end
+
 mnames={}
 function names(root)
  local n=mnames[root]
@@ -246,14 +279,12 @@ function kbd:release(i)
 end
 
 function tostring(any)
- if type(any)=="table" then
+ if (type(any)!="table") return tostr(any)
  local str = "{ "
  for k,v in pairs(any) do
-      str=str..tostring(k).."->"..tostring(v).." "
+  str..=tostring(k).."->"..tostring(v).." "
  end
  return str.."}"
- end
- return tostr(any)
 end
 
 -->8
@@ -269,7 +300,7 @@ function title:draw()
  print("pyrex",32,73,7)
  print("[nyeogmi]",62,73,7)
  print("kistaro",32,79,7)
- local lvlstr = "⬅️ "..start_level.." ➡️"
+ local lvlstr = fmt("⬅️ %v ➡️",start_level)
  print(lvlstr,50,91,1)
  print(lvlstr,51,90,blinkcol) 
 end
@@ -439,8 +470,7 @@ function level:recollide_reanchor()
      not self:mcoll(mx1,my0) and
      not self:mcoll(mx1,my1)
     ) then
-     local key="GEOM"..mx0..","..my0..","..dx..","..dy
-     anch_new[key]= {
+     anch_new[fmt("GEOM%v,%v,%v,%v",mx0,my0,dx,dy)]= {
       max(mx0,mx1),max(my0,my1),adx=-dx,ady=-dy
      }
     end
@@ -448,10 +478,9 @@ function level:recollide_reanchor()
   end
 
   for _,cr in pairs(self._crates) do
-   local key="CRATE"..cr.id..","..dx..","..dy
    local mx0,my0=cr.mx,cr.my
    local mx1,my1=mx0+dx,my0+dy
-   anch_new[key]={
+   anch_new[fmt("CRATE%v,%v,%v",cr.id,dx,dy)]={
     max(mx0,mx1),max(my0,my1),adx=-dx,ady=-dy
    }
   end
@@ -1059,7 +1088,7 @@ function rope:draw(artificial_px,artificial_py)
    if (anch.ady>0) y-=1
   end
   rectfill(x-1,y-1,x+1,y+1,12)
-  print("ax="..n1.ax..",ay="..n1.ay,72,sy)
+  print(fmt("ax=%v,ay=%v",n1.ax,n1.ay),72,sy)
   sy+=7
 
   local n0=n1.prev
@@ -1834,7 +1863,7 @@ function debugmouse:draw3()
  if (c == " ") spr(50,x,y)
  print(c,x,y,15)
  local px, py = mid(0,x,89), mid(0, y > 111 and y - 12 or y + 6, 117)
- print("("..x..", "..y..")\n["..(x\8)..", "..(y\8).."]",px,py,15)
+ print(fmt("(%v, %v)\n[%v, %v]",x,y,x\8,y\8),px,py,15)
  pal()
 end