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. ______________________________________________ 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.
