'\" te
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.TH CPC_SETERRFN 3CPC "Mar 28, 2005"
.SH NAME
cpc_seterrfn \- control libcpc error reporting
.SH SYNOPSIS
.LP
.nf
cc [ \fIflag\fR... ] \fIfile\fR... \(milcpc [ \fIlibrary\fR... ]
#include <libcpc.h>

\fBtypedef void (\fR\fBcpc_errfn_t\fR)(\fBconst char *\fR\fIfn\fR, \fBconst char *\fR\fIfmt\fR, \fBva_list\fR \fIap\fR);
.fi

.LP
.nf
\fBvoid\fR \fBcpc_seterrfn\fR(\fBcpc_errfn_t *\fR\fIerrfn\fR);
.fi

.SH DESCRIPTION
.sp
.LP
For the convenience of programmers instrumenting their code, several
\fBlibcpc\fR(3LIB) functions automatically emit to \fBstderr\fR error messages
that attempt to provide a more detailed explanation of their error return
values.  While this can be useful for simple programs, some applications may
wish to report their errors differently\(emfor example, to a window or to a log
file.
.sp
.LP
The \fBcpc_seterrfn()\fR function allows the caller to provide an alternate
function for reporting errors; the type signature is shown above.  The \fIfn\fR
argument is passed the library function name that detected the error, the
format string \fIfmt\fR and argument pointer \fIap\fR can be passed directly to
\fBvsnprintf\fR(3C) or similar \fBvarargs\fR-based routine for formatting.
.sp
.LP
The default printing routine can be restored by calling the routine with an
\fIerrfn\fR argument of \fINULL\fR.
.SH EXAMPLES
.LP
\fBExample 1 \fRDebugging example.
.sp
.LP
This example produces error messages only when debugging the program containing
it, or when the  \fBcpc_strtoevent()\fR function is reporting an error when
parsing an event specification

.sp
.in +2
.nf
\fBint debugging;
void
myapp_errfn(const char *fn, const char *fmt, va_list ap)
{
        if (strcmp(fn, "strtoevent") != 0 && !debugging)
            return;
        (void) fprintf(stderr, "myapp: cpc_%s(): ", fn);
        (void) vfprintf(stderr, fmt, ap);
}\fR
.fi
.in -2

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT-Level	Unsafe
_
Interface Stability	Obsolete
.TE

.SH SEE ALSO
.sp
.LP
.BR vsnprintf (3C),
.BR cpc (3CPC),
.BR cpc_seterrhndlr (3CPC),
.BR libcpc (3LIB),
.BR attributes (7)
.SH NOTES
.sp
.LP
The \fBcpc_seterrfn()\fR function exists for binary compatibility only. Source
containing this function will not compile. This function is obsolete and might
be removed in a future release. Applications should use
\fBcpc_seterrhndlr\fR(3CPC) instead.