将函数环境设置为函数内部的调用环境(parent.frame) [英] Set a functions environment to that of the calling environment (parent.frame) from within function
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问题描述
helpFunction< -function(){
#can我可以添加一行来改变这个帮助函数的环境到调用函数的那个?
return(importantVar1 + 1)
}
mainFunction< function(importantVar1){
return(helpFunction())
}
mainFunction(importantVar1 = 3)#so这应该输出4
解决方案
嗯,一个函数不能改变它的默认环境,但你可以使用 eval
在不同的环境中运行代码。我不知道这完全符合优雅,但这应该是有效的:
helpFunction< -function(){
eval(quote(importantVar1 + 1),parent.frame())
}
mainFunction< function(importantVar1){
return(helpFunction())
}
mainFunction(importantVar1 = 3)
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
解决方案
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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