如何编写一个通过引用传递变量的漂亮函数？ [英] How to write a nice function that passes variables by reference?

问题描述

如标题中所述，我想在cmake中编写一个 nice函数，该函数能够修改作为参数传递给该函数的变量。

as in said in the title, I would like to write a "nice" function in cmake that is able to modify a variable which is passed as a parameter into that function.

我能想到的唯一方法是丑陋的：

The only way I can think of doing it is ugly:

函数定义

function(twice varValue varName)
set(${varName} ${varValue}${varValue} PARENT_SCOPE)
endfunction(twice)

用法

set(arg foo)
twice(${arg} arg)
message("arg = "${arg})

结果

arg = foofoo

在我看来，没有任何变量可以传递的真实概念？！
我觉得我尚未接受cmake的一些基本知识。

It seems to me, there is no real concept of variables that one can pass around at all?! I feel like there is something fundamental about cmake that I didn't take in yet.

那么，有没有更好的方法呢？

So, is there a nicer way to do this?

非常感谢！

推荐答案

您不需要传递值和变量名。名称就足够了，因为您可以通过名称访问值：

You don't need to pass the value and the name of the variable. The name is enough, because you can access the value by the name:

function(twice varName)
  SET(${varName} ${${varName}}${${varName}} PARENT_SCOPE)
endfunction()

SET(arg "foo")
twice(arg)
MESSAGE(STATUS ${arg})

输出 foofoo

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