[R] Dots in function names

Mike Prager Mike.Prager at noaa.gov
Fri Sep 30 21:29:46 CEST 2005

on 9/30/2005 2:55 PM Peter Dalgaard said the following:

>"Mike Prager" <Mike.Prager at noaa.gov> writes:
>>Recent R function names seem to be using CaseOfTheLetters to mark words 
>>rather than dots as was done previously.  Is the use of dots in function 
>>names deprecated, or is that simply a style choice?  Will function names 
>>with dots cause problems in future revisions?
>Well, come the S4 revolution and dots will cause trouble no more...
>The main reason dots have fallen from grace is that they cause
>ambiguity in relation to S3 methods. In a nutshell: t.test is not a
>transpose method for objects of class "test". Since we check S3
>methods automatically,  it is problematic to keep track of things that
>look like S3 methods without being so. Check out
>.make_S3_methods_stop_list() (in the tools package).
My thanks to Thomas Lumley and Peter Dalgaard for their replies.  Being 
skeptical about software revolutions, I infer that dots will be of some 
concern for a long time.

At the same time, I expect that having names with underscores would 
limit compatibility with S-PLUS. 

As a user, I have not encountered problems with dots, and I don't 
understand whether the concern is likely to apply at the user level.  (I 
was unable to locate the function that P.D. mentioned above.)  Sorry if 
this seems dense, but I am not particularly conversant with the 
internals of R nor experienced in object-oriented programming.

So while I understand Peter's example showing that dots can be 
ambiguous, I am still at a loss as to whether that is of real practical 
concern at a user level; for example, in writing functions that will 
have limited distribution, or for functions that eventually may be 
incorporated into an R package.  I am guessing not, but will appreciate 
more comments if I have that wrong....

Mike Prager

More information about the R-help mailing list