[R] [FORGED] Re: Block comment?

Rolf Turner r.turner at auckland.ac.nz
Sun Sep 3 00:57:26 CEST 2017


On 03/09/17 03:56, William Dunlap via R-help wrote:
> Is the reason you want a block comment containing code (as opposed to
> arbitrary text) that you want to be able to easily run the commented out
> code?  If so the 'if()' construct has the advantage that you only need to
> change code at the start of the comment, not at both ends.
> 
> The if(FALSE) could be if(isTRUE(getOption("DEBUG_ISSUE_XYZ"))) so you
> would not even have to change code to re-enable the debugging code, just
> call options(DEBUG_ISSUE_XYX=TRUE)).


(a) The foregoing is getting too subtle for my feeble brain.

(b) A fundamental problem with the

    if(FALSE) {
       ...
    }

paradigm is that the enclosed code must be syntactically valid, and 
there are certainly situations in which one might wish to comment out 
sections of code that are *not* syntactically valid.  E.g. one might 
wish to comment out *part* of a piece of syntactically valid code for 
the purpose of experimenting with an alternative approach.

cheers,

Rolf

-- 
Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276

> On Sat, Sep 2, 2017 at 7:54 AM, Suzen, Mehmet <msuzen at gmail.com> wrote:
> 
>> AFAIK block comment is not possible
>> it needs to be implemented in R interpreter and defined in the
>> parser.'If' solution is not elegant.
>>
>> On 2 September 2017 at 14:09, Uwe Ligges
>> <ligges at statistik.tu-dortmund.de> wrote:
>>>
>>>
>>> On 02.09.2017 11:40, Christian wrote:
>>>>
>>>> I consider it quite worth while to introduce into R syntax a nestable
>>>> block comment like
>>>>
>>>> #{
>>>> <block of code>
>>>> }#
>>>
>>>
>>> if(FALSE){
>>> <block of code>
>>> }
>>>
>>> Best,
>>> Uwe Ligges
>>>
>>>
>>>> It would make documentation more easily manageable and lucid.
>>>> Is there considerable need for this.
>>>>
>>>> Please, comment on this.
>>>> How about R core?
>>>>
>>>> Christian
>>>
>>>
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>> posting-guide.html
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>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/
>> posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



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