r - 如何修改包中未导出的对象

Question

我的包(我们称之为 A)依赖于另一个包 B。我需要修改一个函数 f在 B 中有一个错误导致我的包失败。问题是f是一个未导出的函数。

如 f已导出，我可以使用 this post 中描述的技术R-帮助:

The few times I want to patch a function like this, I use:

unlockBinding(name, env);
assignInNamespace(name, value, ns=pkgName, envir=env);
assign(name, value, envir=env);
lockBinding(name, env);

但是因为 f未导出，这不起作用。

说明问题的简单例子:

# rf is an exported function from the stats package; this works
foo <- function(x) x
unlockBinding("rf", as.environment("package:stats"))
assignInNamespace("rf", foo, ns="stats", pos="package:stats")
assign("rf", bar, pos="package:stats")
lockBinding("rf", as.environment("package:stats"))

rf(42)
# 42    


# C_rf is an unexported object that rf() uses; this fails
bar <- function(x) x + 1
unlockBinding("C_rf", as.environment("package:stats"))
assignInNamespace("C_rf", bar, ns="stats", pos="package:stats")
assign("C_rf", bar, pos="package:stats")
lockBinding("C_rf", as.environment("package:stats"))

# Error in unlockBinding("C_rf", as.environment("package:stats")) : 
#   no binding for "C_rf"

是否可以修改 f ?

Answer 1

事实证明，我只需要删除 unlockBinding , assign和 lockBinding调用。

bar <- function(x) x + 1
assignInNamespace("C_rf", bar, ns="stats", pos="package:stats")

stats:::C_rf
# function(x) x + 1

rf(3, 2, 2)
#Error in .Call(C_rf, n, df1, df2) : 
#  first argument must be a string (of length 1) or native symbol reference