'\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" '\" RCS: @(#) Panic.3,v 1.3 2003/01/21 19:39:59 hunt Exp '\" .so man.macros .TH Tcl_Panic 3 8.4 Tcl "Tcl Library Procedures" .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME Tcl_Panic, Tcl_PanicVA, Tcl_SetPanicProc, panic, panicVA \- report fatal error and abort .SH SYNOPSIS .nf \fB#include <tcl.h>\fR .sp void \fBTcl_Panic\fR(\fIformat\fR, \fIarg\fR, \fIarg\fR, \fI...\fR) .sp void \fBTcl_PanicVA\fR(\fIformat\fR, \fIargList\fR) .sp void \fBTcl_SetPanicProc\fR(\fIpanicProc\fR) .sp void \fBpanic\fR(\fIformat\fR, \fIarg\fR, \fIarg\fR, \fI...\fR) .sp void \fBpanicVA\fR(\fIformat\fR, \fIargList\fR) .sp .SH ARGUMENTS .AS Tcl_PanicProc *panicProc .AP "CONST char*" format in A printf-style format string. .AP "" arg in Arguments matching the format string. .AP va_list argList in An argument list of arguments matching the format string. Must have been initialized using \fBTCL_VARARGS_START\fR, and cleared using \fBva_end\fR. .AP Tcl_PanicProc *panicProc in Procedure to report fatal error message and abort. .BE .SH DESCRIPTION .PP When the Tcl library detects that its internal data structures are in an inconsistent state, or that its C procedures have been called in a manner inconsistent with their documentation, it calls \fBTcl_Panic\fR to display a message describing the error and abort the process. The \fIformat\fR argument is a format string describing how to format the remaining arguments \fIarg\fR into an error message, according to the same formatting rules used by the \fBprintf\fR family of functions. The same formatting rules are also used by the builtin Tcl command \fBformat\fR. .PP In a freshly loaded Tcl library, \fBTcl_Panic\fR prints the formatted error message to the standard error file of the process, and then calls \fBabort\fR to terminate the process. \fBTcl_Panic\fR does not return. .PP \fBTcl_SetPanicProc\fR may be used to modify the behavior of \fBTcl_Panic\fR. The \fIpanicProc\fR argument should match the type \fBTcl_PanicProc\fR: .PP .CS typedef void Tcl_PanicProc( CONST char *\fBformat\fR, \fBarg\fR, \fBarg\fR,...); .CE .PP After \fBTcl_SetPanicProc\fR returns, any future calls to \fBTcl_Panic\fR will call \fIpanicProc\fR, passing along the \fIformat\fR and \fIarg\fR arguments. To maintain consistency with the callers of \fBTcl_Panic\fR, \fIpanicProc\fR must not return; it must call \fBabort\fR. \fIpanicProc\fR should avoid making calls into the Tcl library, or into other libraries that may call the Tcl library, since the original call to \fBTcl_Panic\fR indicates the Tcl library is not in a state of reliable operation. .PP The typical use of \fBTcl_SetPanicProc\fR arranges for the error message to be displayed or reported in a manner more suitable for the application or the platform. As an example, the Windows implementation of \fBwish\fR calls \fBTcl_SetPanicProc\fR to force all panic messages to be displayed in a system dialog box, rather than to be printed to the standard error file (usually not visible under Windows). .PP Although the primary callers of \fBTcl_Panic\fR are the procedures of the Tcl library, \fBTcl_Panic\fR is a public function and may be called by any extension or application that wishes to abort the process and have a panic message displayed the same way that panic messages from Tcl will be displayed. .PP \fBTcl_PanicVA\fR is the same as \fBTcl_Panic\fR except that instead of taking a variable number of arguments it takes an argument list. The procedures \fBpanic\fR and \fBpanicVA\fR are synonyms (implemented as macros) for \fBTcl_Panic\fR and \fBTcl_PanicVA\fR, respectively. They exist to support old code; new code should use direct calls to \fBTcl_Panic\fR or \fBTcl_PanicVA\fR. .SH "SEE ALSO" abort(3), printf(3), exec(n), format(n) .SH KEYWORDS abort, fatal, error