R devel - May 2008 - value returned by findFun when the name cannot be found.

Dear list,

I have been using "findVar" (defined in src/main/envir.c) happily and
would like to use
"findFun".

However I have trouble when the name searched cannot be found: while
"findVar" returns R_UnboundValue,
"findFun" does not (the 4 last lines of "findFun" are copied
below).

    error(_("could not find function \"%s\""),
CHAR(PRINTNAME(symbol)));
    /* NOT REACHED */
    return R_UnboundValue;
}

I assume that the comment "/* NOT REACHED */ means that R_UnboundValue
is not returned... and my question is:
what is returned then ? (I am a little lost in the nested calls within
"error").


Thanks,


Laurent

On Sat, 24 May 2008, Laurent Gautier wrote:
> Dear list,
>
> I have been using "findVar" (defined in src/main/envir.c) happily
and
> would like to use
> "findFun".
>
> However I have trouble when the name searched cannot be found: while
> "findVar" returns R_UnboundValue,
> "findFun" does not (the 4 last lines of "findFun" are
copied below).
>
>    error(_("could not find function \"%s\""),
CHAR(PRINTNAME(symbol)));
>    /* NOT REACHED */
>    return R_UnboundValue;
> }
>
> I assume that the comment "/* NOT REACHED */ means that R_UnboundValue
> is not returned... and my question is:
> what is returned then ? (I am a little lost in the nested calls within
"error").
There is no returned -- the call to 'error' will result in a non-local
exit (executed via longjmp).  The return statement is there to keep
the C compiler happy since it doesn't know about this property of
error and so would issue a warning, ant the /* NOT REACHED */ comment
here (and elswehere) remindes us of this.

Best,

luke
>
>
> Thanks,
>
>
> Laurent
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
-- 
Luke Tierney
Chair, Statistics and Actuarial Science
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
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