"Jonathan Scott Duff" <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > On Wed, Jan 29, 2003 at 11:32:53AM -0800, Michael Lazzaro wrote: > > > > Agreed, it's not pretty. The fundamental problem is that a primitive > > like an C<int> simply cannot be undefined... there's no flag for that > > (which is they're primitive.) > > The solution I advocate is to allow even "primitive" types to hold > undef. I don't have an implementation, but that's just a detail I'll > leave to those actually doing the implementation :-) > > > A simple solution is perhaps to say that C<is default> can only be > > applied to types that can be undef (scalar,ref,Int,Str...) and can't be > > used on things that have no undefined state (bit,int,str...).
C++ had a design principle: you only pay for what you ask for. From a different perspective: if you ask for it, then you're willing to pay. So if you ask for a default on an array of primitive types, then the implementation assumes that you're willing to pay for it: but only for those arrays that have defaults. The fact of the default is a property of the array, not of the elements it stores. There's no need to add undef values to primitive types. The most obvious solution (obvious =/=> best) is a boolean (bit) array whose elements are associated with elements in the data array. Yes, there's a cost, but if the programmer asks for something, then they pay for it. But the implementation guys aren't allowed to play bait-and-switch! Dave. -- http://dave.whipp.name
