Tcl8.5.19/Tk8.5.19 Documentation > TclLib > Panic

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NAME

Tcl_Panic, Tcl_PanicVA, Tcl_SetPanicProc - report fatal error and abort

SYNOPSIS

#include <tcl.h>

void

Tcl_Panic(format, arg, arg, ...)

void

Tcl_PanicVA(format, argList)

void

Tcl_SetPanicProc(panicProc)

ARGUMENTS

DESCRIPTION

SEE ALSO

KEYWORDS

NAME

SYNOPSIS

ARGUMENTS

const char* format (in)

A printf-style format string.

arg (in)

Arguments matching the format string.

va_list argList (in)

An argument list of arguments matching the format string. Must have been initialized using va_start, and cleared using va_end.

Tcl_PanicProc *panicProc (in)

Procedure to report fatal error message and abort.

DESCRIPTION

In a freshly loaded Tcl library, Tcl_Panic prints the formatted error message to the standard error file of the process, and then calls abort to terminate the process. Tcl_Panic does not return.

Tcl_SetPanicProc may be used to modify the behavior of Tcl_Panic. The panicProc argument should match the type Tcl_PanicProc:

typedef void Tcl_PanicProc(
        const char *format,
        arg, arg,...);

After Tcl_SetPanicProc returns, any future calls to Tcl_Panic will call panicProc, passing along the format and arg arguments. To maintain consistency with the callers of Tcl_Panic, panicProc must not return; it must call abort. panicProc should avoid making calls into the Tcl library, or into other libraries that may call the Tcl library, since the original call to Tcl_Panic indicates the Tcl library is not in a state of reliable operation.

The typical use of Tcl_SetPanicProc 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 wish calls Tcl_SetPanicProc 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).

Although the primary callers of Tcl_Panic are the procedures of the Tcl library, Tcl_Panic 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.

Tcl_PanicVA is the same as Tcl_Panic except that instead of taking a variable number of arguments it takes an argument list.

SEE ALSO

KEYWORDS