If an optional parameter is omitted in the midle of a function, you have to add an extra comma, so why not
ask Ruud to make a stricter syntaxchecking for UDF's, personally i would like that to be an option:
Strict On/Off

Example, Function DoSomeThing($a,Optional $b, Optional $c):

This is legal(Strict Off, normal way of KiXtart):

$Res = DoSomeThing($a,$b,$c)
$Res = DoSomeThing($a,$b)
$Res = DoSomeThing($a,,$c)
$Res = DoSomeThing($a)


Whith a stricter syntax checking it should read like this, to be accepted(Strict On):

$Res = DoSomeThing($a,$b,$c)
$Res = DoSomeThing($a,$b,)
$Res = DoSomeThing($a,,$c)
$Res = DoSomeThing($a,,)

I just found cj's idea so good, that i have made this for my UDF liblary:

code:
Function SubString($String, $Start, Optional $Len)
   $SubString = ""
   If VarType($String) <> 8
      Return
   EndIf
   If VarType($Start) <> 3
      Return
   EndIf
   If VarType($Len) <> 3
      $Len = Len($String) - $Start + 1
   EndIf
   $SubString = SubStr($String, $Start, $Len)
EndFunction

Erik

rhowarth and Fuse, what do you think about this idea! (Of course Ruud would have to agree in making this option)