R devel - Sep 2018 - Suggestion: use mustWork = TRUE as the default for system.file

Hello all,

Currently, the default behavior for system.file() is to return "" for
faulty paths.

I've found this behavior to be difficult when debugging, since it passes
the empty path onto other functions.  I initially wrote in errors myself
(with code like `if(path == "") stop(?Path not found?)`), but I now
use
mustWork=TRUE or fs::path_package(), which errors by default.

What are the general thoughts on this issue?  I would love to
see mustWork=TRUE become the default in future versions of R, but
I would be happy to hear any counterarguments (or support!) for this
suggestion.

Cheers,
Irene Steves

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Hello Irene,

we can only change the documented behavior when there is a very strong 
reason to do so, because it indeed can break existing code. A lot of 
existing code would depend on the current behavior, using e.g. nzchar() 
to check the output of system.file(). Changing the behavior that is used 
on error paths would be particularly tricky, because the error paths are 
typically not covered by tests (normally when considering a change I 
would run tests for all CRAN+BIOC packages to test if that change would 
be too disruptive, but it would not help in this case). I am afraid such 
a change is impossible.

Best
Tomas

On 09/14/2018 02:16 AM, Irene Steves wrote:
> Hello all,
>
> Currently, the default behavior for system.file() is to return ""
for
> faulty paths.
>
> I've found this behavior to be difficult when debugging, since it
passes
> the empty path onto other functions.  I initially wrote in errors myself
> (with code like `if(path == "") stop(?Path not found?)`), but I
now use
> mustWork=TRUE or fs::path_package(), which errors by default.
>
> What are the general thoughts on this issue?  I would love to
> see mustWork=TRUE become the default in future versions of R, but
> I would be happy to hear any counterarguments (or support!) for this
> suggestion.
>
> Cheers,
> Irene Steves
>
> 	[[alternative HTML version deleted]]
>
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