bionic (3) Tcl_CancelEval.3tcl.gz

NAME

       Tcl_CancelEval, Tcl_Canceled - cancel Tcl scripts

SYNOPSIS

       #include <tcl.h>
       int
       Tcl_CancelEval(interp, resultObjPtr, clientData, flags)

       int
       Tcl_Canceled(interp, flags)

ARGUMENTS

       Tcl_Interp *interp (in)          Interpreter in which to cancel the script.

       Tcl_Obj *resultObjPtr (in)       Error  message  to  use  in  the  cancellation, or NULL to use a default
                                        message. If  not  NULL,  this  object  will  have  its  reference  count
                                        decremented before Tcl_CancelEval returns.

       int flags (in)                   ORed  combination  of  flag  bits  that specify additional options.  For
                                        Tcl_CancelEval, only  TCL_CANCEL_UNWIND  is  currently  supported.   For
                                        Tcl_Canceled, only TCL_LEAVE_ERR_MSG and TCL_CANCEL_UNWIND are currently
                                        supported.

       ClientData clientData (in)       Currently reserved for future use.  It should be set to NULL.
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DESCRIPTION

       Tcl_CancelEval cancels or unwinds the script in progress soon after the next invocation  of  asynchronous
       handlers,  causing TCL_ERROR to be the return code for that script.  This function is thread-safe and may
       be called from any thread in the process.

       Tcl_Canceled checks if the script in progress  has  been  canceled  and  returns  TCL_ERROR  if  it  has.
       Otherwise,  TCL_OK  is returned.  Extensions can use this function to check to see if they should abort a
       long running command.  This function is thread sensitive and may only  be  called  from  the  thread  the
       interpreter was created in.

   FLAG BITS
       Any  ORed  combination  of  the following values may be used for the flags argument to procedures such as
       Tcl_CancelEval:

       TCL_CANCEL_UNWIND   This flag is used by Tcl_CancelEval and Tcl_Canceled.  For  Tcl_CancelEval,  if  this
                           flag  is  set,  the  script  in progress is canceled and the evaluation stack for the
                           interpreter is unwound.  For Tcl_Canceled,  if  this  flag  is  set,  the  script  in
                           progress  is  considered  to  be  canceled  only  if  the  evaluation  stack  for the
                           interpreter is being unwound.

       TCL_LEAVE_ERR_MSG   This flag is only used by Tcl_Canceled; it is ignored by  other  procedures.   If  an
                           error is returned and this bit is set in flags, then an error message will be left in
                           the interpreter's  result,  where  it  can  be  retrieved  with  Tcl_GetObjResult  or
                           Tcl_GetStringResult.   If  this flag bit is not set then no error message is left and
                           the interpreter's result will not be modified.

SEE ALSO

       interp(3tcl), Tcl_Eval(3tcl), TIP 285

KEYWORDS

       cancel, unwind