Thanks for the report, I am testing a patch that will allow multi-line arguments to user macros.

Best
Tomas

On 05/25/2018 04:45 PM, Georgi Boshnakov wrote:
While on the topic of Rd macro arguments, it seems that  if a multiline 
argument is supplied, the lines after the first are silently ignored:

f <- tempfile()
mac6 <- "\\newcommand{\\mac6}{mac6: #1}"

cat(mac6, "\\mac6{2*3
2+2
sin(pi)
}\n", file = f)
rd <- tools::parse_Rd(f)

rd
  mac6: 2*3

---

Georgi Boshnakov


-----Original Message-----
From: Tomas Kalibera [mailto:tomas.kalib...@gmail.com]
Sent: 25 May 2018 10:05
To: Georgi Boshnakov; r-devel@r-project.org
Subject: Re: [Rd] Rd parser throws error for user macros invoked with empty 
argument

Thanks for the report and the examples - and they do not have to be that
verbose, it is enough to just define and use a command, e.g.

cat("\\newcommand{\\mac1}{MAC1:#1}\\mac1{}", file=f)
rd <- tools::parse_Rd(f)

Whenever you get an error message like "Value of SET_STRING_ELT() must
be a 'CHARSXP' not a 'NULL'", there is a bug (at least the error message
should be relevant/informative).

I am testing a patch that will allow empty arguments to macros (they
will expand to an empty string, like in LaTeX).

Best
Tomas

On 05/14/2018 11:23 PM, Georgi Boshnakov wrote:
Bug or feature?

I get the following error from parse_Rd() when a user Rd macro (including 
system ones) is invoked with empty argument {},
eg \mymacro{}:

Error in tools::parse_Rd(fn) :
    Value of SET_STRING_ELT() must be a 'CHARSXP' not a 'NULL'

A full example is further below with the system macro \CRANpkg{}. In this 
example it doesn't make sense to use empty argument but the error is not 
specific to this particular macro.

------
Georgi Boshnakov


Create an Rd file containing system macro \CRANpkg{bibtex}, parse_Rd() is ok:

=================
fn <- tempfile()
writeLines("\\name{dummyfun}
\\alias{dummyfun}
\\title{Dummy title}
\\description{Dummy description}
\\usage{
dummyfun(x, ...)
}
\\arguments{
    \\item{x}{a value.}
    \\item{\\dots}{further arguments.}
}
\\details{
      \\CRANpkg{bibtex}
}
", fn)

tools::parse_Rd(fn)
...
\details{
      \href{{https://CRAN.R-project.org/package=bibtex}{\pkg{bibtex}}}
}

================

With empty argument - \CRANpkg{} - Rd parser throws error. Of course it is 
silly in this example but I have used it with other user defined  macros where 
it may make sense to have empty argument.

================
writeLines("\\name{dummyfun}
\\alias{dummyfun}
\\title{Dummy title}
\\description{Dummy description}
\\usage{
dummyfun(x, ...)
}
\\arguments{
    \\item{x}{a value.}
    \\item{\\dots}{further arguments.}
}
\\details{
      \\CRANpkg{}
}
", fn)
tools::parse_Rd(fn)
Error in tools::parse_Rd(fn) :
    Value of SET_STRING_ELT() must be a 'CHARSXP' not a 'NULL'

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