[fpc-pascal] WHY compiler should be public?

[Xiangrong Fang]

2013/10/25 Michael Van Canneyt <michael at freepascal.org>

> Why not simply make it a procedure that is called by ver-2 and ver-3.
>
> If it cannot be called directly from external code, and will called only
> from inside a visible consructor, there is simply no reason to make this
> procedure a constructor. A simple procedure will do.


​Because I don't know how to make it non-constructor. See the following
code:

  1 unit wtree;
  2 {$mode objfpc}{$H+}
  3 interface
  4 uses tree;
  5 type
  6   TQWordTree = specialize TTree<QWord>;
  7   TWTree = class(TQWordTree)
  8   private
  9     FModel: string;
 10   public
 11     property Model: string read FModel;
 12     constructor Create(AData: QWord; AParent: TWTree; AModel: string);
 13     constructor Create(HeadNode, TailNode: QWord);
 14   end;
 15 implementation
 16
 17 constructor TWTree.Create(AData: QWord; AParent: TWTree; AModel:
string);
 18 begin
 19   inherited Create(AData, AParent);
 20   FModel := AModel;
 21 end;
 22
 23 constructor TWTree.Create(HeadNode, TailNode: QWord);
 24 begin
 25   inherited Create(0, nil);
 26   Data := HeadNode;
 27   with TWTree do Create(TailNode, Create(HeadNode, Self, 'h'), 't');
 28   FModel := 'R';
 29 end;
 30
 31 end.

Please tell me how to deal with line 27, which called the should-be-private
constructor.

BTW, this code uses TTree class, which is here:

https://github.com/xrfang/fpcollection/blob/master/src/units/tree.pas

Also, ​

​I don't understand why this does not work:

f := TFileStream.Create;

I know that TFileStream's Create require a file name parameter, but as
TFileStream is inherited from TObject, which has a Create without
parameter.  This is why I feel that it is possible to HIDE a public
constructor from ancestor.

Best Regards,
Xiangrong​
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