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Tcl_Panic(3)		    Tcl	Library	Procedures		  Tcl_Panic(3)


       Tcl_Panic, Tcl_PanicVA, Tcl_SetPanicProc	- report fatal error and abort

       #include	<tcl.h>

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

       Tcl_PanicVA(format, argList)


       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
					      va_start,	  and	cleared	 using

       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 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

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

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

       abort, fatal, error

Tcl				      8.4			  Tcl_Panic(3)


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