insertSource()错误:“未找到对象'.cacheOnAssign'" [英] Error with insertSource(): "object '.cacheOnAssign' not found"

问题描述

我正在尝试使用功能insertSource(R 2.12中的新增功能)来更新我进行了更改的功能.

I am trying to use the function insertSource (new in R 2.12) to update a function that I have made changes on.

但是，当我以这种方式使用该功能时:

However, when I use the function in this way:

insertSource('filename.R', package = 'mypackage')

我得到了错误:

Error in get(this, envir = envp) : object '.cacheOnAssign' not found

不幸的是，我无法提出一个简单的可重现的示例-如果有帮助，请提出如何执行的示例-但我发现以下代码确实有效:

Unfortunately I can not come up with a simple reproducible example - if one would be helpful, please suggest how I can do it - but I have found that the following code does work:

system("echo 'nls <- function(nls) return(nls)' > foo.R")
insertSource('foo.R', package = stats)

stats软件包和mypackage之间的一个区别是库的位置(mypackage在'〜/lib/R/'中.( update )):当.libPaths('~/lib/R')在，然后在Google搜索".cacheOnAssign"时仅返回6个匹配，其中两个匹配此问题.

One difference between the stats package and mypackage is the library location (mypackage is in '~/lib/R/'. (update): error still occurs when .libPaths('~/lib/R') is in .Rprofile, and googleing '.cacheOnAssign' only returns 6 hits, two of them to this question.

1. 该错误是什么意思?
2. 如何使用insertSource?

调试

使用options(error = recover)

options(error = recover) 
Error in get(this, envir = envp) : object '.cacheOnAssign' not found
Called from: get(this, envir = envp)
Browse[1]> where
where 1: get(this, envir = envp)
where 2: insertSource("filename.R", "mypackage")
Browse[1]> ls()
[1] "q"
Browse[1]> n
>

不确定这些结果是什么，以及从这里去哪里

not sure what to make of these results, and where to go from here

使用options(error = browser)可以提供我放置在文本文件中的更多信息

using options(error = browser) gives more information that I have placed in a text file

推荐答案

这可以说是insertSource()中的错误.当您提供文件而不是环境时，它在文件上调用evalSource()，该文件在源环境中合成了.cacheOnAssign变量(简称为FALSE).因为变量不一定存在于程序包名称空间中，所以替换操作很麻烦.

This is arguably a bug in insertSource(). When you supply a file instead of an environment, it calls evalSource() on the file which synthesizes the .cacheOnAssign variable (it will be simply FALSE) in the source environment. That chokes the replacement since the variable does not necessarily exist in the package namespace.

有几种解决方法，最简单的方法是自己创建环境并像在此修复程序中那样删除.cacheOnAssign:

There are several ways around this, probably the easiest is to create the environment yourself and remove .cacheOnAssign like in this fix:

insertSource <- function(source, package="", ...) {
    if (!is(source, "environment")) {
        source <- evalSource(source, package = package, lock = FALSE)
        rm(.cacheOnAssign, envir = source)
    }
    methods::insertSource(source, package = package, ...)
}

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