Sharing the same unit between projects

[Rollo62]

The problem with missing include files is very annoying.
You have the possibility to add a define in the IDE global project options, defines section for each project.
E.g.
Global Define: _X_USE_MY_UNITS

Delphi-Quellcode:

{$IF DEFINED( _X_USE_MY_UNITS ) }
{$INCLUDE MyUnit }  //<== declares maybe _X_USE_MY_SPECIAL_UNIT_1, ...
{$ENDIF }

Uses
{$IF DEFINED( _X_USE_MY_SPECIAL_UNIT_1 ) }
    MySpecialUnit1,
{$ENDIF }
{$IF DEFINED( _X_USE_MY_SPECIAL_UNIT_2 ) }
    MySpecialUnit2,
{$ENDIF }
{$IF DEFINED( _X_USE_MY_SPECIAL_UNIT_3 ) }
    MySpecialUnit3,
{$ENDIF }
   ...
{$IF     DEFINED( MY_VARIANT_UNIT_1 ) }
    MyVariantUnit1,
{$ELSEIF DEFINED( MY_VARIANT_UNIT_2 ) }
    MyVariantUnit2,
{$ELSEIF DEFINED( MY_VARIANT_UNIT_3 ) }
    MyVariantUnit3,
{$ENDIF }

    LastUnit
  ;

Would be much nicer, if could be detected if Include file is declared or not.