[fpc-devel] Thoughts on being able to declare "pointer-to-type" parameters directly in method signatures?

[Ben Grasset]

For example, consider the following code, that implements a generic
"memcpy"-style procedure using a static advanced-record method:

program Example;

{$mode Delphi}

type
  TMem<T> = record
  public type
    PT = ^T;
  public
    class procedure Copy(Dest: PT; Src: PT; Len: PtrUInt); static; inline;
  end;

  class procedure TMem<T>.Copy(Dest: PT; Src: PT; Len: PtrUInt);
  begin
    while Len > 0 do begin
      Dest^ := Src^;
      Inc(Dest);
      Inc(Src);
      Dec(Len);
    end;
  end;

type
  String4 = String[4];

var
  X: TArray<String4> = ['AAAA', 'BBBB', 'CCCC', 'DDDD', 'EEEE'];
  Y: TArray<String4> = ['', '', '', '', ''];
  S: String4;

begin
  TMem<String4>.Copy(@Y[0], @X[0], 5);
  for S in Y do WriteLn(S);
end.

The only reason the record is necessary at all is to be able to declare
"PT" as a pointer type alias to the record's overall "T".

Personally, I'd much rather simply write the following, if it was possible:

procedure MemCopy<T>(Dest: ^T; Src: ^T; Len: PtrUInt);
begin
  while Len > 0 do begin
    Dest^ := Src^;
    Inc(Dest);
    Inc(Src);
    Dec(Len);
  end;
end;

Of course, currently that's not valid code. This kind of thing is useful
for more than just generics, also: it would be just as applicable to
non-generic records, primitive types, e.t.c.

Surely I can't be the only one who has ever wanted to use a "typed pointer"
without first having to declare a named alias.

So I guess my questions are:

A) How feasible is this to implement?

B) Is there a specific reason is has *not* been implemented previously?
(Seems unlikely)
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