从接口访问参数 (Fortran) [英] Access a parameter from an interface (Fortran)

问题描述

我正在使用一个参数来修复所用类型的精度.在我尝试在界面中使用相同的类型之前，这很好用.考虑这个小例子:

I am using a parameter to fix the precision of the used types. This works fine until I try to use the same type within an interface. Consider this small example:

module Hello
    implicit none

    save
    integer, parameter  :: K = selected_real_kind(10)

contains

    subroutine dosomething(fun)
        real(K)     :: foo
        interface
           function fun(bar)
                real(K) :: bar
                real(K) :: fun
           end function fun
        end interface
    end subroutine

end module

在这里，foo 将是所需的类型，而编译器 (gfortran) 会抱怨 'bar' 和 'fun'.

Here, foo would be of the desired type, whereas the compiler (gfortran) complains for 'bar' and 'fun'.

错误是

Error: Parameter 'k' at (1) has not been declared or is a variable, which does 
not reduce to a constant expression

有没有办法让它工作?(目前，我只是到处写 selected_real_kind(10) 但这一点都不优雅)

Is there a way to get this working? (For now, I am just writing selected_real_kind(10) everywhere but this is not elegant at all)

谢谢！

推荐答案

最简单的方法是在界面中添加import.模块的定义超出了接口的范围，这有点设计错误.普通的 import 将导入所有内容.

The easiest way is to add import inside the interface. It is somewhat of a misdesign that the definitions of the module are outside the scope of the interface. Plain import will import everything.

....
    subroutine dosomething(fun)
        real(K)     :: foo
        interface
           function fun(bar)
                import
                real(K) :: bar
                real(K) :: fun
           end function fun
        end interface
    end subroutine
....

也可以:import :: K

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