R devel - Aug 2009 - c() poor error reporting (PR#13917)

Full_Name: Michael Spiegel
Version: 2.9.1
OS: linux
Submission from: (NULL) (137.54.6.192)


The function c() gives a cryptic error message if an "empty" argument
is
accidentally passed to the function.  The expression c(,,,) yields the error
message "argument is missing, with no default".  For comparison, the
expression
sum(,,,) yields the error message "element 1 is empty; the part of the args
list
of 'sum' being evaluated was: (, , , )".  This type of error was
produced by
accidentally typing an expression similar to "sum(c(,1,2,3))" which
was a
sub-expression inside a much larger expression spanning tens of lines.  When the
entire expression was evaluated, the error message "argument is missing,
with no
default" provides little context for determining the cause of the error.

On 28/08/2009 5:00 PM, michael.m.spiegel at gmail.com
wrote:
> Full_Name: Michael Spiegel
> Version: 2.9.1
> OS: linux
> Submission from: (NULL) (137.54.6.192)
> 
> 
> The function c() gives a cryptic error message if an "empty"
argument is
> accidentally passed to the function. 
I wouldn't call that cryptic. You put in a blank argument, and it told 
you the argument was missing.

The expression c(,,,) yields the error
> message "argument is missing, with no default".  For comparison,
the expression
> sum(,,,) yields the error message "element 1 is empty; the part of the
args list
> of 'sum' being evaluated was: (, , , )".  This type of error
was produced by
> accidentally typing an expression similar to "sum(c(,1,2,3))"
which was a
> sub-expression inside a much larger expression spanning tens of lines. 
When the
> entire expression was evaluated, the error message "argument is
missing, with no
> default" provides little context for determining the cause of the
error.
Yes, sum() is more friendly in its error reporting.  This hardly 
qualifies as a bug, but if you want to submit a patch, it would be 
considered.

Duncan Murdoch