Tcl_Panic(3tcl) Tcl Library Procedures Tcl_Panic(3tcl)
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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 for-
mat 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 de-
bugger instead. If the windows executable does not have a stderr chan-
nel (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 indi-
cates 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 exten-
sion 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(3tcl), format(3tcl)
KEYWORDS
abort, fatal, error
Tcl 8.4 Tcl_Panic(3tcl)
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