Hi Bill, Thanks. I think we can define the function in the environment whose parent environment is empty environment. But don't know how.
Best, Mike 2013/9/12 William Dunlap <wdun...@tibco.com> > If you want to find out if you've forgotten to make 'a' an argument > you can use codetools::findGlobals(func) to list the names that don't > refer to something already defined in the 'func': > > fun <- function(b) a + b > > library(codetools) > > findGlobals(fun) > [1] "+" "a" > You need to filter out things defined in some attached package (like the > "+" > from the base package). I think that when you run 'R CMD check' on a > package this sort of check is made on the functions in the package. > findGlobals does not run the function to make its checks, it just looks at > the function. > > A kludgy way to get an error message instead of having the function > silently > use something from .GlobalEnv is to make the environment of the function > the parent of .GlobalEnv > > a <- 1000 > > environment(fun) <- parent.env(globalenv()) > > fun(7) > Error in fun(7) : object 'a' not found > Since this is a run-time check it will not find problems in branches of the > code that are not run. The parent environment of .GlobalEnv changes > every time you attach or detach a package. For production code you will > want to use a package - the namespace mechanism and the check command > will take care of most of this sort of problem. > > Bill Dunlap > Spotfire, TIBCO Software > wdunlap tibco.com > > > > -----Original Message----- > > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] > On Behalf > > Of Sarah Goslee > > Sent: Thursday, September 12, 2013 2:09 PM > > To: Gang Peng > > Cc: r-help@r-project.org > > Subject: Re: [R] How to avoid searching variables in global environment > > > > Hi, > > > > You need to specify that a is an argument to the function: > > > > On Thu, Sep 12, 2013 at 3:56 PM, Gang Peng <michael.gang.p...@gmail.com> > wrote: > > > For example: > > > > > > a <- 1 > > > > > > f <- function(b){ > > > return(a+b) > > > } > > > > > > > f <- function(b, a) { > > return(a+b) > > } > > > > > when we call function f(2), r will search the local environment first, > if > > > it cannot find a, it will search global environment, and return 3. How > to > > > avoid r searching the global environment and return an error when we > call > > > this function? > > > > The function will now give an error if a is not specified. > > > > Sarah > > > > -- > > Sarah Goslee > > http://www.functionaldiversity.org > > > > ______________________________________________ > > R-help@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
