On Monday, July 30, 2012 23:44:56 cybevnm wrote: > During initializing Variant, D discards top level const of array, which > leads to little unintuitive behaviour. Consider code: > > import std.stdio; > import std.variant; > void main() > { > const int[] arr; > Variant v = Variant( arr ); > writeln( v.peek!( typeof( arr ) )() ); > writeln( v.peek!( const(int)[] )() ); > writeln( v.type() ); > } > > ...and output: > %dmd main.d && ./main.d > null > 7FFF358AE298 > const(int)[] > > As you can see peek works successfully not for original array type, but > for type without top level const. Is Variant supposed to work in that way ?
Probably not. When arrays are passed to templated functions, they're passed as tail-const (so the constness on the array itself - but not its elements - is stripped), which in general is _way_ more useful than passing them as fully const. However, Variant predates that behavior by quite a while, and it's well-passed due for having extensive work done on its implementation (it's API should be fine, but it was implemented when D was much younger, and we can do a much better job of it now). There's a discussion on that in the main newsgroup at the moment actually. In any case, please create a bug report for this: http://d.puremagic.com/issues - Jonathan M Davis