Tcl_Panic(3) Tcl Library Procedures Tcl_Panic(3)______________________________________________________________________________NAME
Tcl_Panic, Tcl_PanicVA, Tcl_SetPanicProc, panic, panicVA - report fatal
error and abort
Tcl_Panic(format, arg, arg, ...)
panic(format, arg, arg, ...)
CONST char* format (in) A printf-style format string.
arg (in) Arguments matching the format
va_list argList (in) An argument list of arguments
matching the format string.
Must have been initialized using
TCL_VARARGS_START, and cleared
Tcl_PanicProc *panicProc (in) Procedure to report fatal error
message and abort.
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 builtin 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.
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,
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 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
Tcl_PanicVA is the same as Tcl_Panic except that instead of taking a
variable number of arguments it takes an argument list. The procedures
panic and panicVA are synonyms (implemented as macros) for Tcl_Panic
and Tcl_PanicVA, respectively. They exist to support old code; new
code should use direct calls to Tcl_Panic or Tcl_PanicVA.
SEE ALSOabort(3), printf(3), exec(n), format(n)KEYWORDS
abort, fatal, error
Tcl 8.4 Tcl_Panic(3)