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Tcl_Panic(3)		    Tcl	Library	Procedures		  Tcl_Panic(3)

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NAME
       Tcl_Panic,  Tcl_SetPanicProc, Tcl_ConsolePanic -	report fatal error and
       abort

SYNOPSIS
       #include	<tcl.h>

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

       const char *
       Tcl_SetPanicProc(panicProc)

       Tcl_ConsolePanic(format,	arg, arg, ...)

ARGUMENTS
       const char* format (in)		      A	printf-style format string.

	arg (in)			      Arguments	 matching  the	format
					      string.

       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.

       If your application doesn't use Tcl_Main	or Tk_Main and you want	to im-
       plicitly	 use  the  stderr channel of your application's	C runtime (in-
       stead of	the stderr channel of the C runtime used by Tcl), you can call
       Tcl_SetPanicProc	with Tcl_ConsolePanic as its  argument.	 On  platforms
       which  only  have  one  C runtime (almost all platforms except Windows)
       Tcl_ConsolePanic	is equivalent to NULL.

       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  result  of Tcl_SetPanicProc	is the full Tcl	version	with build in-
       formation (e.g.,	9.0.0+abcdef...abcdef.gcc-1002).

       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.

       Tcl_SetPanicProc	can not	be used	in stub-enabled	extensions.

       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.

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

KEYWORDS
       abort, fatal, error

Tcl				      8.4			  Tcl_Panic(3)

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