[R] using reserved words in R, and reuse variable names in different functions

[William Dunlap]

> See fortune("dog").
To wit:
  "Firstly, don't call your matrix 'matrix'. Would you call your dog 'dog'? Anyway, it might clash with the function 'matrix'"

I once had a cat named "kitty" and she never had a problem with it.

Clashes between non-functions and functions that cause problems are not that common.  With 4000 packages, each with a number of functions, it is hard to avoid using a name that someone has used for a function.

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 Rolf Turner
> Sent: Saturday, March 02, 2013 5:01 AM
> To: Sarah Goslee
> Cc: r-help
> Subject: Re: [R] using reserved words in R, and reuse variable names in different
> functions
> 
> On 03/02/2013 01:12 PM, Sarah Goslee wrote:
> > On Fri, Mar 1, 2013 at 7:06 PM, C W <tmrsg11 at gmail.com> wrote:
> >> Thanks, that was just an example I came up with.  I was just curious if
> >> using same variable names in different functions would cause problems.
> > No. The environment of a function is independent of other functions.
> >
> >>   Especially with reserved words.
> > Yes. Using reserved words can cause all kinds of subtle problems. Avoid it.
> >
> 
> Very sound advice.  But it should be noted that "t", "c", and "matrix"
> to which
> the OP referred are *not* technically reserved words.  Nonetheless their use
> as names of user-defined objects should be eschewed.  See fortune("dog").
> 
> You *can't* actually assign values to reserved words.  E.g.
> 
>      TRUE <- 42
> 
> throws an error.  (Whereas matrix <- 42, bad form though it may be,
> does not throw an error.)
> 
>      cheers,
> 
>          Rolf Turner
> 
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