[R] How to comment in R

Wacek Kusnierczyk Waclaw.Marcin.Kusnierczyk at idi.ntnu.no
Wed Feb 11 20:27:52 CET 2009


Duncan Murdoch wrote:
> On 2/11/2009 1:21 PM, Stavros Macrakis wrote:
>> On Wed, Feb 11, 2009 at 12:32 PM, Greg Snow <Greg.Snow at imail.org> wrote:
>>> ...The c-style of /* */ allows both types and you can comment out
>>> part of a line, but it is not simple to match and has its own
>>> restrictions.  Friedl in his regular expressions book takes 10 pages
>>> to develop a pattern to match these (and the final pattern is almost
>>> 2 full lines of text in the book).  And this is without allowing
>>> nesting....
>>
>> Though there is a real debate about the value of multiline, possibly
>> nested, comments, the regular expression argument is a red herring.
>> Lexical analysis of multiline comments is a solved problem (and not a
>> particularly difficult one!), and matters only to language and editor
>> implementors.  Emacs handles them with no problem.
>
> I agree about that.  I think the lack of multiline comments comes from
> design considerations rather than implementation ones.   They're just
> not needed, and having two types of comments would lead to weird
> interactions, e.g. is the block comment closed in the lines below?
>
>   /*
> #  */

it's still a simple design decision which, once made, can be implemented
coherently.

vQ



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