通过C函数定义的Fortran派生类型构造函数 [英] Fortran derived type constructor defined though C function

问题描述

我想通过C函数定义派生类型构造函数。在下面的例子中，我设法通过C接口定义一个重载的加法运算符。尽管语法非常相似，但构造函数的定义在gfortran 4.9下失败，出现以下错误：

I want to define a derived type constructor through a C function. In the following example, I managed to defined a overloaded addition operator through a C interface. Altough the syntax is quite similar, the definition of the constructor fails under gfortran 4.9 with the following error:

test.f90:7.52:

    module procedure my_module_fortran_new_my_double
                                                    1
Error: 'my_module_fortran_new_my_double' at (1) is not a module procedure

经过一段时间的谷歌搜索或者在堆栈溢出的前一篇文章，我没有找到任何解决方案。如果有人能告诉我是什么触发了这个错误以及如何纠正错误，我会非常高兴。

After some time spend in googling or looking at previous post at stack overflow, I did not find any solution. I would be very pleased if someone could tell me what triggers this error and how to correct it.

以下是我的模块的源代码：

Here is the source code of my module:

module my_module
  use iso_c_binding
  type, bind(c) :: my_double
     real(c_double) :: x
  end type my_double
  interface my_double
    module procedure my_module_fortran_new_my_double
  end interface
  interface operator (+)
     module procedure my_module_fortran_add
  end interface operator (+)
  interface
     type(my_double) function my_module_fortran_new_my_double (v) bind ( c )
       use iso_c_binding
       import :: my_double
       real (c_double), intent(in) :: v
     end function my_module_fortran_new_my_double
     type(my_double) function my_module_fortran_add (v1,v2) bind ( c )
       use iso_c_binding
       import :: my_double
       type (my_double), intent(in) :: v1,v2
     end function my_module_fortran_add
  end interface
end module my_module

推荐答案

外部过程不是模块过程。我想这就是你想要的：

An external procedure isn't a module procedure. I think this is what you want:

module my_module
  use iso_c_binding
  type, bind(c) :: my_double
     real(c_double) :: x
  end type my_double

    interface
       type(my_double) function my_module_fortran_new_my_double (v) bind ( c )
         use iso_c_binding
         import :: my_double
         real (c_double), intent(in) :: v
       end function my_module_fortran_new_my_double
       type(my_double) function my_module_fortran_add (v1,v2) bind ( c )
         use iso_c_binding
         import :: my_double
         type (my_double), intent(in) :: v1,v2
       end function my_module_fortran_add
  end interface

  interface my_double
   procedure my_module_fortran_new_my_double
  end interface
  interface operator (+)
    procedure :: my_module_fortran_add
  end interface operator (+)

end module my_module

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