Scroll to navigation

Tcl_Panic(3tcl) Tcl Library Procedures Tcl_Panic(3tcl) 





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.
    
    

    

  








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(3tcl), format(3tcl)






KEYWORDS


abort, fatal, error







  

    8.4
    Tcl