Assignment overloading of the form scalar = vector(:)

[FlyingHermes]

Hi,

I'm having trouble to define a overloaded assigment using:

1. a scalar variable on the left-hande side and
2. a 1d array on the right-hand side.

In other words, I want to do scalar = vector(:).

Is this even allowed ?

Thanks.

! ifort main.f90; ./a.out

Module MyModule
  implicit none
  private
  public        ::      MyType
  
  Type          ::      MyType
    integer     ::      Var
  contains
    generic     ,public         ::      operator(+)     =>      Addition_0d, Addition_1d
    procedure   ,private        ::      Addition_0d
    procedure   ,private        ::      Addition_1d
    generic     ,private        ::      assignment(=)   =>      Assign_0d, Assign_1d
    procedure   ,private        ::      Assign_0d
    procedure   ,private        ::      Assign_1d
  End Type
  contains
  
Function Addition_0d( This, That ) result(Res)
  class(MyType)                 ,intent(in)     ::      This
  type(MyType)                  ,intent(in)     ::      That
  type(MyType)                                  ::      Res
  Res%Var       =       This%Var + That%Var
End Function 

Function Addition_1d( This, That ) result(Res)
  class(MyType)                 ,intent(in)     ::      This
  type(MyType)  ,dimension(:)   ,intent(in)     ::      That
  type(MyType)                                  ::      Res
  Res%Var       =       This%Var + sum( That%Var )
End Function

Subroutine Assign_0d( lhs, rhs )
  class(MyType)                 ,intent(out)    ::      lhs
  type(MyType)                  ,intent(in)     ::      rhs
  lhs%Var       =       rhs%Var
End Subroutine

Subroutine Assign_1d( lhs, rhs )
  class(MyType)                 ,intent(out)    ::      lhs
  type(MyType)  ,dimension(:)   ,intent(in)     ::      rhs
  lhs%Var       =       sum( rhs%Var )
End Subroutine

End Module

Program Main
  use MyModule  ,only:  MyType
  implicit none
  
  type(MyType)                  ::      Sca_1, Sca_2, Sca_3
  type(MyType)  ,dimension(3)   ::      Vec_1_2_3
  
  Sca_1%Var = 1
  Sca_2%Var = 2
  Sca_3%Var = 0
  
  write(*,"(/,'Test_1)')")
  Sca_3 = Sca_1 + Sca_2
  if ( Sca_3%Var == 3 ) then
    write(*,"('Success: Sca_3%Var = ',g0)") Sca_3%Var
  else
    write(*,"('Failure: Sca_3%Var = ',g0)") Sca_3%Var
  end if
  
  Sca_3%Var        = 0
  Vec_1_2_3(1)%Var = 1
  Vec_1_2_3(2)%Var = 2
  Vec_1_2_3(3)%Var = 3
  
  write(*,"(/,'Test_2)')")
  Sca_3 = Sca_1 + Vec_1_2_3
  if ( Sca_3%Var == 7 ) then
    write(*,"('Success: Sca_3%Var = ',g0)") Sca_3%Var
  else
    write(*,"('Failure: Sca_3%Var = ',g0)") Sca_3%Var
  end if
  
  Sca_3%Var = 0
  write(*,"(/,'Test_3')")
  Sca_3 = Vec_1_2_3                     ! COMPILER_ERROR: error #6366: The shapes of the array expressions do not conform.   [SCA_3]
  if ( Sca_3%Var == 6 ) then
    write(*,"('Success: Sca_3%Var = ',g0)") Sca_3%Var
  else
    write(*,"('Failure: Sca_3%Var = ',g0)") Sca_3%Var
  end if
  
End Program

[Steven_L_Intel1]

The assignment operator is marked private. You need to make it public otherwise it isn't usable outside the module. The first assignment works because it is assigning a scalar to a scalar and that's intrinsic.

[FlyingHermes]

Oooups... of course. I didn't double-checked the code.

Sorry for that.