[R-pkg-devel] How to Document and S3 Method for the Parenthesis Class?

[Duncan Murdoch]

On 07/11/2019 9:35 a.m., bill using denney.ws wrote:
> Hi,
> 
>   
> 
> Short version of the question:  How does one document a method for the "("
> class in a .Rd file?
> 
>   
> 
> Details:
> 
> I recently contributed to the digest package functions to assist with
> generating sha1 hashes for formula objects.  Sometimes within formula, the
> parenthesis ("(") class is used, for example [1]:
> 
>   
> 
>> class((a~(b+c))[[3]])
> 
> [1] "("
> 
>   
> 
> So, I wrote a method to handle that class, too.  When trying to document it
> in the .Rd file, I tried the following code, but when checking the
> documentation, it gets an error:
> 
>   
> 
> \method{sha1}{"("}(x, digits = 14, zapsmall = 7, ..., algo = "sha1")

I think this should work:

   \method{sha1}{`(`}(x, digits = 14, zapsmall = 7, ..., algo = "sha1")

A quick test case gave me errors from not documenting the args, but not 
the bad \usage line error described below.

Duncan Murdoch

> 
>   
> 
> The error when checking the documentation is:
> 
>   
> 
>> checking Rd \usage sections ... WARNING
> 
>    Bad \usage lines found in documentation object 'sha1':
> 
>      <unescaped bksl>method{sha1}{"("}(x, digits = 14, zapsmall = 7, ...,
> algo = "sha1")
> 
>    
> 
>    Functions with \usage entries need to have the appropriate \alias
> 
>    entries, and all their arguments documented.
> 
>    The \usage entries must correspond to syntactically valid R code.
> 
>    See chapter 'Writing R documentation files' in the 'Writing R
> 
>    Extensions' manual.
> 
>   
> 
> I have tried variants of escaping the parenthesis like "\(" and "\\(" and
> the unescaped variant "(", too.
> 
>   
> 
> Thanks,
> 
>   
> 
> Bill
> 
>   
> 
> [1] In case the first thought is, "don't write formula which have a full
> side within redundant parentheses", something equivalent to this was created
> by update.formula().
> 
> 
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> 
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