Very Simple Struct Storage System Code

import std.stdio;
import std.traits: isAssignable, isCopyable, hasIndirections, Unqual;
import std.meta : AliasSeq, Filter, NoDuplicates;
import core.lifetime : forward;
import std.sumtype: SumType;
import io ;

version(none)
{
  alias Result(T) = SumType!(T, Error);
}

auto
mod11(int i)
{
  int r = i % 11 ;
  if ( r )
    return err!int(ERR.TEST, "not modulo");
    //    return err!int(551);
  //       return err!void(551);

  return ok!int( r );
}

auto
pfce(int i)
{
  static int s ;
  if ( i )
    {
      s = i ;
      return ok!(void*)(&s) ;
    }
  if ( i == 82 )
    return err!(void*)(ERR.TEST ,"too ugly #");
  
 return err!(void*)(57) ;
}

class C
{
  int i ;
  this(int ii)
  {
    this.i = ii ;
  }
  RV!C
  add(int j)
  {
    if ( j % 2 )
      return err!C(ERR.TEST);
    this.i += j  ;
    return ok!C(null);
  }
}

int
main()
{
  version ( re_less_match ) {
  string[] n = [ "abcd.h" , "efgh.zc"  ] ;

  string[] match = [ ".h", ".zc" ] ;
  
  foreach ( nth, a ; n )
    {
      string[2] tail ;
      tail[0] = a[$-2..$] ;
      tail[1] = a[$-3..$] ;

      foreach( i, m ; match )
	foreach( j, t ; tail )
	  if ( m == t )
	    writeln("MATCHES! ", i, "/", j, "," , match[j], " => ", n[nth] );
    }
  }
  
  auto rv = mod11(33);
  writeln("Got : ", rv );
  assert(rv);
  assert(!rv.isErr);
  assert(rv.hasValue);
  assert(!rv.hasError);
  assert(rv.value == 0);
  writeln("Got : ", rv.hasError );
  
  auto rv2 = mod11(42);
  writeln("Got : ", rv2 );
  assert(rv2.isErr);
  assert(!rv2.hasValue);
  assert(rv2.hasError);
  //  assert(rv2.error == "not modulo");
  assert(rv2.error == ERR.TEST);
  writeln("Msg: ", rv2.getmsg );
  
  int ival = 42 ;
  auto p = pfce(ival);
  if (p.isErr)
    writeln("E pfce : ", p.error , " ", p.getmsg );
  else
    writeln("pfce : ", typeof(p.value).stringof , " ", p.value );
  return 0 ;
}

/* Local Variables: */
/* mode: d */
/* buffer-save-without-query: t */
/* End: */