[R-pkg-devel] Avoid reprocessing Rmd vignette

[Dirk Eddelbuettel]

On 18 March 2018 at 21:57, Tim Keitt wrote:
| That's a great idea, however my problem is with building a vignette, not
| running tests, unless they are linked in some way I'm not understanding.

Similar idea applies: condition, just as Inaki and Thierry suggested.  An
example for a conditional vignette evaluation is 

```{r echo = FALSE, message = FALSE}`r ''`
hasData <- requireNamespace("hurricaneexposuredata", quietly = TRUE)                #1
if (!hasData) {                                                                     #2
    knitr::opts_chunk$set(eval = FALSE)                                             #3
    msg <- paste("Note: Examples in this vignette require that the", 
                 "`hurricaneexposuredata` package be installed. The system",
                 "currently running this vignette does not have that package",
                 "installed, so code examples will not be evaluated.")
    msg <- paste(strwrap(msg), collapse="\n")
    message(msg)                                                                    #4
}
```

and the paper (https://journal.r-project.org/archive/2017/RJ-2017-026/) by
Brooke Anderson and myself discusses #1 to #4.

Dirk

-- 
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