Tcl_Panic(3) Tcl Library Procedures Tcl_Panic(3)

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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

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.
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DESCRIPTION

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 Tcl_Panic to
display a message describing the error and abort the process. The
format argument is a format string describing how to format the
remaining arguments arg into an error message, according to the same
formatting rules used by the printf family of functions. The same
formatting rules are also used by the built-in Tcl command format.

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. On
Windows, when a debugger is running, the formatted error message is
sent to the debugger instead. If the windows executable does not have
a stderr channel (e.g. wish.exe), then a system dialog box is used to
display the panic message.

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. 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.

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

abort(3), printf(3), exec(n), format(n)

KEYWORDS

abort, fatal, error

Tcl 8.4 Tcl_Panic(3)