From pauljohn32 at gmail.com  Sat Apr  9 21:51:34 2011
From: pauljohn32 at gmail.com (Paul Johnson)
Date: Sat, 9 Apr 2011 14:51:34 -0500
Subject: [Rd] Wish there were a "strict mode" for R interpreter. What about
	You?
Message-ID: <BANLkTim=6ae2huv+GYQLMtgs2P+GD8_WtA@mail.gmail.com>

Years ago, I did lots of Perl programming. Perl will let you be lazy
and write functions that refer to undefined variables (like R does),
but there is also a strict mode so the interpreter will block anything
when a variable is mentioned that has not been defined. I wish there
were a strict mode for checking R functions.

Here's why. We have a lot of students writing R functions around here
and they run into trouble because they use the same name for things
inside and outside of functions. When they call functions that have
mistaken or undefined references to names that they use elsewhere,
then variables that are in the environment are accidentally used. Know
what I mean?

dat <- whatever

someNewFunction <- function(z, w){
   #do something with z and w and create a new "dat"
   # but forget to name it "dat"
    lm (y, x, data=dat)
   # lm just used wrong data
}

I wish R had a strict mode to return an error in that case. Users
don't realize they are getting nonsense because R finds things to fill
in for their mistakes.

Is this possible?  Does anybody agree it would be good?

-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas



[Rd] Wish there were a "strict mode" for R interpreter. What about You?
Paul Johnson