Functions: GR_start_error(), GR_report_error(), GR_end_error()

These three functions are the GRASP error handlers. Their use is best illustrated by example. A typical usage is shown below - a fragment taken from a fictitous routine called ``trouble()".

...
GR_start_error("trouble()",rcsid,__FILE__,__LINE__);
GR_report_error("The GR_report_error() function is like printf().\n");
GR_report_error("It can have no arguments.\n");
GR_report_error("It can have a float argument %f\n",x1);
GR_report_error("Or any mixture of valid types %d %d %s\n",i1,i2,stringptr);
GR_end_error();
...

The use of these three routines as shown will print out, for example:

GRASP: Message from function trouble() at line number 123 of file "source.c".
The GR_report_error() function is like printf().
It can have no arguments.
It can have a float argument 5.43210
Or any mixture of valid types -2 17 the string pointed to by the pointer
$Id: man_utility.tex,v 1.38 1999/07/11 21:22:18 ballen Exp $
$Name:  $

In particular, the line number, release number, and file name are all filled in automatically. The environment variables that govern the behavior of the default error handler are shown in Table  below.

Table: The behavior of the error handler is determined by three environment variables, which can be set and un-set using the shell commands setenv and unsetenv. These permit the error messages to be turned off, saved in a file, and control the file name and its over-write properties.

Environment variable.	How to set, and effect obtained.
GRASP_NODEBUG	setenv GRASP_NODEBUG $\qquad \qquad \qquad$ turns off error messages.
GRASP_ERRORFILE	setenv GRASP_ERRORFILE thisfile sends errors to file ``thisfile".
GRASP_ERRORFILE_OVERWRITE	setenv GRASP_ERRORFILE_OVERWRITE errors don't accumulate in file.