从界面访问参数(Fortran) [英] Access a parameter from an interface (Fortran)

问题描述

我正在使用一个参数来固定所使用类型的精度. 直到我尝试在接口中使用相同的类型，此方法才能正常工作.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)则抱怨"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

是否有办法使它正常工作? (目前，我只是在各处编写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

最简单的方法是在接口内添加import.模块的定义超出了接口的范围，这在某种程度上是一种错误的设计.普通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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