[R] Define "local" function

[Ales Ziberna]

I am also very interested how this could be done, possibly in such a way 
that this would be incorporated in the function itself and there wouldn't be 
a need to write "environment(f) <- NULL" before calling a function, as is 
proposed in the reply below and in a thread a few days ago!

Thanks for any suggestions,
Ales Ziberna

----- Original Message ----- 
From: "Gabor Grothendieck" <ggrothendieck at gmail.com>
To: <fsaldanha at alum.mit.edu>
Cc: "Submissions to R help" <r-help at stat.math.ethz.ch>
Sent: Friday, April 15, 2005 5:05 PM
Subject: Re: [R] Define "local" function


> On 4/15/05, Fernando Saldanha <fsaldan1 at gmail.com> wrote:
>> I discovered a bug in a program I am writing which was due to the
>> program using a global variable within a function.
>>
>> For example,
>>
>> myfunc <- function(x) { y}
>>
>> That is, I made a mistake when defining the function and wrote "y"
>> when I should have written "x".
>>
>> However, there was a variable y in the global environment and the
>> function "worked" but gave the wrong answer.
>>
>> I would like to avoid this problem by defining a "local" function.
>> That would mean a function that only accepts as variables those that
>> were defined within its body or were passed as parameters, and would
>> generate an error when I try to define it if I am using an "external"
>> variable. Something like:
>>
>> > myfunc <- function(x, type = 'local') { y}
>> Error: using external variable
>>
>> I read the documentation about environments (I still do not understand
>> a lot of it, have been working with R for four days now), and searched
>> the newsgroups, but I could not find the way to do this.
>>
>> Thanks for any suggestions.
>>
>
> Try this:
>
>> y <- 3
>> f <- function(x) y
>> environment(f) <- NULL
>> f(1)
> Error in f(1) : Object "y" not found
>
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