如何在fortran中覆盖结构构造函数 [英] How to override a structure constructor in fortran

问题描述

目前是否可以覆盖 Fortran 中的结构构造函数?我见过这样的提议示例(例如在 Fortran 2003 规范中):

Is it currently possible to override the structure constructor in Fortran? I have seen proposed examples like this (such as in the Fortran 2003 spec):

module mymod

  type mytype
    integer :: x
    ! Other stuff
  end type

  interface mytype
    module procedure init_mytype
  end interface

contains
  type(mytype) function init_mytype(i)
    integer, intent(in) :: i
    if(i > 0) then
      init_mytype%x = 1
    else
      init_mytype%x = 2
    end if
  end function
end

program test
  use mymod
  type(mytype) :: x
  x = mytype(0)
end program

由于冗余变量名称，这基本上会产生一堆错误(例如，错误:'mytype' 的 DERIVED 属性与 (1) 处的 PROCEDURE 属性冲突).Fortran 2003 示例的逐字副本会生成类似的错误.我已经在 gfortran 4.4、ifort 10.1 和 11.1 中尝试过，它们都产生了相同的错误.

This basically generates a heap of errors due to redundant variable names (e.g. Error: DERIVED attribute of 'mytype' conflicts with PROCEDURE attribute at (1)). A verbatim copy of the fortran 2003 example generates similar errors. I've tried this in gfortran 4.4, ifort 10.1 and 11.1 and they all produce the same errors.

我的问题:这只是 fortran 2003 的一个未实现的功能吗?还是我错误地实施了这个?

My question: is this just an unimplemented feature of fortran 2003? Or am I implementing this incorrectly?

我遇到了错误报告和针对此问题发布了 gfortran 补丁.但是，我尝试使用 11 月构建的 gcc46，但没有运气和类似错误.

I've come across a bug report and an announced patch to gfortran regarding this issue. However, I've tried using a November build of gcc46 with no luck and similar errors.

编辑 2:上面的代码似乎可以使用 Intel Fortran 12.1.0.

Edit 2: The above code appears to work using Intel Fortran 12.1.0.

推荐答案

我查阅了我的 Fortran 2008 标准副本.这确实允许您定义一个与派生类型同名的通用接口.我的编译器(Intel Fortran 11.1)不会编译代码，所以我怀疑(手头没有 2003 标准的副本)这是 Fortran 2003 标准的一个尚未实现的功能.

I consulted my copy of the Fortran 2008 standard. That does allow you to define a generic interface with the same name as a derived type. My compiler (Intel Fortran 11.1) won't compile the code though so I'm left suspecting (without a copy of the 2003 standard to hand) that this is an as-yet-unimplemented feature of the Fortran 2003 standard.

除此之外，您的程序中存在错误.您的函数声明:

Besides that, there is an error in your program. Your function declaration:

  type(mytype) function init_mytype
    integer, intent(in) :: i

指定函数规范中不存在的参数的存在和意图，它或许应该重写为:

specifies the existence and intent of an argument which is not present in the function specification, which should perhaps be rewritten as:

  type(mytype) function init_mytype(i)

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