Fetching and Saving warnings from a function

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?withCallingHandlers

E.g.,
R> f <- function(expr) {
      warnings <- character()
      withCallingHandlers(expr, warning=function(e){
         warnings <<- c(warnings, conditionMessage(e))
         invokeRestart("muffleWarning")
      })
      warnings
}
R> f(1:10)
character(0)
R> f(warning("Hmm"))
[1] "Hmm"
R> f({warning("Hmm"); x <- 666 ; warning("Possible problem")})
[1] "Hmm"              "Possible problem"
R> x
[1] 666

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of Christofer Bogaso
Sent: Wednesday, June 12, 2013 12:07 PM
To: r-help
Subject: [R] Fetching and Saving warnings from a function

Hello again,

Let say I have following user defined function:

Myfn <- function(x) {
if (x < 0) {
warning("Negative value")
}
return(x)
}

Now I want to create some function which will save the Warnings from
'Myfn', so that I can use those warnings later for more analysis. Therefore
I was thinking of following type of function:

ProposedWarningStoreFunction <- function() {
                  .........            ............        ...........
}

therefore,if I run 'ProposedWarningStoreFunction', I should get following
kind of results:

Warnings <- ProposedWarningStoreFunction({Result <- Myfn(-4)})

Result
 -4

Warnings
In Myfn(-3) : Negative value

Can somebody here point me how to achieve this? Or is it possible to
achieve at all?

Thank you for your help.

	[[alternative HTML version deleted]]

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