从函数内部将函数环境设置为调用环境(parent.frame)的环境 [英] Set a functions environment to that of the calling environment (parent.frame) from within function

问题描述

我仍在为 R 范围界定和环境而苦苦挣扎.我希望能够构建从我的主"函数中调用的简单辅助函数，这些函数可以直接引用这些主函数中的所有变量——但我不想在我的每个主函数中定义辅助函数职能.

I am still struggling with R scoping and environments. I would like to be able to construct simple helper functions that get called from my 'main' functions that can directly reference all the variables within those main functions - but I don't want to have to define the helper functions within each of my main functions.

helpFunction<-function(){
#can I add a line here to alter the environment of this helper function to that of the calling function?
return(importantVar1+1)
}

mainFunction<-function(importantVar1){
return(helpFunction())
}

mainFunction(importantVar1=3) #so this should output 4

推荐答案

嗯，一个函数不能改变它的默认环境，但是你可以使用 eval 在不同的环境中运行代码.我不确定这是否完全符合优雅的条件，但这应该可以:

Well, a function cannot change it's default environment, but you can use eval to run code in a different environment. I'm not sure this exactly qualifies as elegant, but this should work:

helpFunction<-function(){
    eval(quote(importantVar1+1), parent.frame())
}

mainFunction<-function(importantVar1){
    return(helpFunction())
}

mainFunction(importantVar1=3)

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