创建 R 闭包的单独副本

Question

有没有一种方法可以将闭包复制到一个新对象，该对象包含原始闭包的当前状态，同时还可以针对环境中所有即将发生的更改进行分离？

我试图提出一个解决方案，但当我尝试使用包含的函数时，它失败并出现错误：

Error in { : could not find function "{"

这是一个代码示例：

# basic incrementation closure
inc <- function() {
  i <- 0 
  
  function(x = 1) {
    i <<- i + x
    i
  }
}

copyClosure <- function(x) {
  oldEnv <- environment(x)
  
  # set up copy of x in new env
  ret <- x
  newEnv <- new.env(parent = emptyenv())
  environment(ret) <- newEnv
  
  # copy objects from old to new env
  objs <- ls(envir = oldEnv, all.names = TRUE, sorted = FALSE)
  for (ii in objs) assign(x = ii, envir = newEnv, value = get(x = ii, envir = oldEnv))
  
  return(ret)
}

# original closure object
foo <- inc()
foo(5)

bar <- copyClosure(foo)

# check if objects i are identical
identical(x = get(x = "i", envir = environment(foo)),
          y = get(x = "i", envir = environment(bar)))

# check if objects i are separated
foo(5)
identical(x = get(x = "i", envir = environment(foo)),
          y = get(x = "i", envir = environment(bar)))

# try using copied closure
bar(5)

Answer 1

更改新环境的父环境以匹配旧环境

newEnv <- new.env(parent = parent.env(oldEnv))

然后它似乎按预期工作。