Tcl_BackgroundException man page on Archlinux

Man page or keyword search:  
man Server   11224 pages
apropos Keyword Search (all sections)
Output format
Archlinux logo
[printable version]

Tcl_BackgroundError(3)	    Tcl Library Procedures	Tcl_BackgroundError(3)

______________________________________________________________________________

NAME
       Tcl_BackgroundException,	 Tcl_BackgroundError  -	 report	 Tcl exception
       that occurred in background processing

SYNOPSIS
       #include <tcl.h>

       Tcl_BackgroundException(interp, code)

       Tcl_BackgroundError(interp)

ARGUMENTS
       Tcl_Interp *interp (in)		Interpreter  in	 which	the  exception
					occurred.

       int code (in)			The  exceptional  return  code	to  be
					reported.
_________________________________________________________________

DESCRIPTION
       This procedure is typically invoked when a Tcl  exception  (any	return
       code  other  than TCL_OK) occurs during “background processing” such as
       executing an event handler.  When such an exception occurs, the	condi‐
       tion  is reported to Tcl or to a widget or some other C code, and there
       is not usually any obvious way for that code to report the exception to
       the  user.   In these cases the code calls Tcl_BackgroundException with
       an interp argument identifying the interpreter in which	the  exception
       occurred,  and  a  code	argument  holding the return code value of the
       exception.  The state of the interpreter, including any	error  message
       in  the interpreter result, and the values of any entries in the return
       options dictionary, is  captured	 and  saved.   Tcl_BackgroundException
       then  arranges for the event loop to invoke at some later time the com‐
       mand registered in that interpreter to handle background errors by  the
       interp  bgerror command, passing the captured values as arguments.  The
       registered handler command is meant  to	report	the  exception	in  an
       application-specific  fashion.	The handler command receives two argu‐
       ments, the result of the interp, and the return options of  the	interp
       at  the	time the error occurred.  If the application registers no han‐
       dler command, the default handler command will attempt to call  bgerror
       to  report  the error.  If an error condition arises while invoking the
       handler command, then Tcl_BackgroundException reports the error	itself
       by printing a message on the standard error file.

       Tcl_BackgroundException does not invoke the handler command immediately
       because this could potentially  interfere  with	scripts	 that  are  in
       process	at  the time the error occurred.  Instead, it invokes the han‐
       dler command later as an idle callback.

       It is possible for many background exceptions to accumulate before  the
       handler	command is invoked.  When this happens, each of the exceptions
       is processed in order.  However, if the handler command returns a break
       exception,  then	 all  remaining	 error reports for the interpreter are
       skipped.

       The Tcl_BackgroundError routine is an older and simpler interface  use‐
       ful  when  the  exception code reported is TCL_ERROR.  It is equivalent
       to:

	      Tcl_BackgroundException(interp, TCL_ERROR);

KEYWORDS
       background, bgerror, error, interp

Tcl				      7.5		Tcl_BackgroundError(3)
[top]

List of man pages available for Archlinux

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net