在R中的tryCatch'ed错误中获取堆栈跟踪 [英] get stack trace on tryCatch'ed error in R

问题描述

这与其他一些问题有关，但我似乎无法弄清楚如何应用答案，所以我在问一个新问题。

This is related to some other questions, but I can't seem to figure out how to apply the answer, so I'm asking a new question.

我试图从一段看起来像这样的代码中找出一个不知情的错误：

I'm trying to figure out an uninformative error from a piece of code that looks like this:

tryCatch(MainLoop(), 
  error=function(e) { fatal(lgr, paste('caught fatal error:', as.character(e))); 
                      exit.status <<- 1 })

问题是该错误似乎与库函数中隐藏的东西有关：

The problem is that the error appears to be related to something buried in a library function:

Error in nrow(x): (subscript) logical subscript too long

nrow 不在我的代码中，因为上面的C级错误只适用于一种从未发生过的索引在任何我的 nrow 调用。

That nrow is not in my code, as the C-level error above only applies to a type of indexing that never happens in any of my nrow calls.

所以我真的很想从那个 tryCatch 。这是一个类似的问题：

So I'd really like to get a stack trace from within that tryCatch. Here's an analogous problem:

x <- function() { y(); }
y <- function() { z(); }
z <- function() { stop("asdf") }

> x()
Error in z() : asdf
> tryCatch(x(), error=function(e) { print(conditionCall(e)) } )
z()
> tryCatch(x(), error=function(e) { dump.frames() } )
> last.dump
$`tryCatch(x(), error = function(e) {
    dump.frames()
})`
<environment: 0x1038e43b8>

$`tryCatchList(expr, classes, parentenv, handlers)`
<environment: 0x1038e4c60>

$`tryCatchOne(expr, names, parentenv, handlers[[1]])`
<environment: 0x1038e4918>

$`value[[3]](cond)`
<environment: 0x1038ea578>

attr(,"error.message")
[1] "asdf"
attr(,"class")
[1] "dump.frames"

如何获取包含调用 y（）的堆栈跟踪， ？我必须停止使用 tryCatch ？什么是更好的方法？

How do I get the stack trace that includes the call to y()? Do I have to stop using tryCatch? What's a better way?

推荐答案

对于交互式使用可能 trace（stop，quote（print .calls（））））在 stop（）调用时打印调用堆栈。

For interactive use one might trace(stop, quote(print(sys.calls()))) to print the call stack at the time stop() is invoked.

从？tryCatch ，

 The function 'tryCatch' evaluates its expression argument in a
 context where the handlers provided in the '...'  argument are
 available.

而

 Calling handlers are established by 'withCallingHandlers'...
 the handler is called... in the context where the condition
 was signaled...

so

>     withCallingHandlers(x(), error=function(e) print(sys.calls()))
[[1]]
withCallingHandlers(x(), error = function(e) print(sys.calls()))

[[2]]
x()

[[3]]
y()

[[4]]
z()

[[5]]
stop("asdf")

[[6]]
.handleSimpleError(function (e) 
print(sys.calls()), "asdf", quote(z()))

[[7]]
h(simpleError(msg, call))

Error in z() : asdf

如果有一个内部的tryCatch

This is thwarted if there is an inner tryCatch

withCallingHandlers({
    tryCatch(x(), error=function(e) stop("oops"))
}, error=function(e) print(sys.calls()))

，因为我们只有在tryCatch处理错误后才能访问调用堆栈。

as we only have access to the call stack after the tryCatch has 'handled' the error.

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