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Cancel(3)               Tcl Library Procedures               Cancel(3)




NAME

       Tcl_CancelEval, Tcl_Canceled - cancel Tcl scripts


SYNOPSIS

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

       int
       Tcl_Canceled(interp, flags)


ARGUMENTS

       Interpreter  in  which  to cancel the script.  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.   Cur-
       rently, reserved for future use.  It should be set to NULL.


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.  Exten-
       sions 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_Can-
                              celed.  For Tcl_CancelEval, if this flag is set,
                              the script in progress is canceled and the eval-
                              uation 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_GetO-
                              bjResult  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

       TIP 285


KEYWORDS

       cancel, unwind



Tcl                                   8.6                        Cancel(3)

tcl 8.6.0 - Generated Sun Jan 13 09:01:31 CST 2013
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