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digitalmars.D.bugs - [Issue 1383] New: Implicit Function Instantiation with typesafe-variadic of delegates doesn't work

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1383

           Summary: Implicit Function Instantiation with typesafe-variadic
                    of delegates doesn't work
           Product: D
           Version: 1.020
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: webmaster villagersonline.com


I have a template function, with a single Tuple template parameter, where the
arguments to the function are typesafe variadic delegates, where each delegate
takes arguments defined by the Tuple.  It will not implicitly deduce the
elements of the Tuple:


CODE
================
/* parts of Curry() taken from the digitalmars.com template examples */
void delegate(U) Curry(A, U...)(void delegate(A,U) dg,A arg)
{
  struct ArgRecord {
    A arg;
    typeof(dg) callback;

    void OpCall(U args) { callback(arg,args); }
  }
  auto temp = new ArgRecord;
  temp.arg = arg;
  temp.callback = dg;
  return &temp.OpCall;
}


/* the intent of this template is to take 2 or more delegates with the
 * the same argument types and return a new delegate which will call
 * each delegate in sequence, passing it the arguments delivered.
 */
void delegate(A) Seq(A...)(void delegate(A)[] dgs...)
{
  return Curry(delegate void(void delegate(A)[] dgs1,A args)
               {
                 foreach(dg; dgs1)
                   dg(args);
               },
               dgs);
}



struct Foo {
  void fred(int i) {}
}


void main() {
  void delegate(int) tmp;
  auto bob = new Foo;
  auto dan = new Foo;

  tmp = Seq!(int)(&bob.fred);             // this works
  tmp = Seq!(int)(&bob.fred, &dan.fred);  // this works
  tmp = Seq      (&bob.fred);             // this doesn't
  tmp = Seq      (&bob.fred, &dan.fred);  // neither does this
}
=========

DMD OUTPUT:
=========
baz.d(45): template baz.Seq(A...) does not match any template declaration
baz.d(45): template baz.Seq(A...) cannot deduce template function from argument
types (void delegate(int))
baz.d(45): Error: cannot implicitly convert expression
((Seq(A...))((&(*bob).fred))) of type int to void delegate(int)
baz.d(46): template baz.Seq(A...) does not match any template declaration
baz.d(46): template baz.Seq(A...) cannot deduce template function from argument
types (void delegate(int),void delegate(int))
baz.d(46): Error: cannot implicitly convert expression
((Seq(A...))((&(*bob).fred),(&(*dan).fred))) of type int to void delegate(int)



Note that the template works fine if I explicitly instantiate it.


-- 
Jul 27 2007
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1383





------- Comment #1 from wbaxter gmail.com  2008-03-11 16:34 -------
Actually it's much simpler than all that.  IFTI with plain old typesafe
variadic doesn't work.

void foo(T)(T[] x ...) {
}

void main() {
    foo(2,7,4);
}

iftivariadic.d(23): template iftivariadic.foo(T) does not match any function
template declaration
iftivariadic.d(23): template iftivariadic.foo(T) cannot deduce template
function from argument types !()(int,int,int)


-- 
Mar 11 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1383


bugzilla digitalmars.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED




------- Comment #2 from bugzilla digitalmars.com  2008-06-22 18:52 -------
Fixed dmd 1.031 and 2.015


-- 
Jun 22 2008
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1383


webmaster villagersonline.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |VERIFIED




------- Comment #3 from webmaster villagersonline.com  2008-06-23 12:14 -------
Fix confirmed.


-- 
Jun 23 2008