>>>>> Ben Bolker <bbol...@gmail.com>
>>>>> on Thu, 15 Sep 2011 11:03:26 +0200 writes:
> Inspired by
>
http://stackoverflow.com/questions/7487778/could-you-tell-me-what-this-error-means
> I wrote the following very small (one-line) patch which
> returns an *informative* error message when R tries to
> load a zero-byte file rather than
> Error in if (!grepl("RD[AX]2\n", magic)) { : argument is
> of length zero
> I would guess that error messages with the word "magic"
> in them would be disturbing to new users, who are probably
> worried already that R is magic ...
:-) indeed...
While it would not be a good idea to program around such error
messages in general, as each extra if(...) is executed everytime
the function is called, i.e. has a (albeit *very small*) penalty for
every correct call just for the sake of that message in the
erronous call case,
I do agree that it is worth here and so have added it (for
R-devel only).
Thank you, Ben.
> Ben Bolker
> ----------------------------------------------------------------------
> Index: load.R
> ===================================================================
> --- load.R (revision 56743)
> +++ load.R (working copy)
> @@ -25,6 +25,7 @@
> ## Since the connection is not open this opens it in binary mode
> ## and closes it again.
> magic <- readChar(con, 5L, useBytes = TRUE)
> + if (length(magic)==0) stop("empty (zero-byte) file")
> if (!grepl("RD[AX]2\n", magic)) {
> ## a check while we still know the call to load()
> if(grepl("RD[ABX][12]\r", magic))
>
> ----------------------------------------------------------------------
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
