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diff --git a/doc/BackgdErr.3 b/doc/BackgdErr.3 new file mode 100644 index 0000000..005f5b6 --- /dev/null +++ b/doc/BackgdErr.3 @@ -0,0 +1,58 @@ +'\" +'\" Copyright (c) 1992-1994 The Regents of the University of California. +'\" Copyright (c) 1994-1996 Sun Microsystems, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +'\" SCCS: @(#) BackgdErr.3 1.3 96/03/25 19:56:51 +'\" +.so man.macros +.TH Tcl_BackgroundError 3 7.5 Tcl "Tcl Library Procedures" +.BS +.SH NAME +Tcl_BackgroundError \- report Tcl error that occurred in background processing +.SH SYNOPSIS +.nf +\fB#include <tcl.h>\fR +.sp +\fBTcl_BackgroundError\fR(\fIinterp\fR) +.SH ARGUMENTS +.AS Tcl_Interp *interp +.AP Tcl_Interp *interp in +Interpreter in which the error occurred. +.BE + +.SH DESCRIPTION +.PP +This procedure is typically invoked when a Tcl error occurs during +``background processing'' such as executing an event handler. +When such an error occurs, the error condition 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 error to the user. +In these cases the code calls \fBTcl_BackgroundError\fR with an +\fIinterp\fR argument identifying the interpreter in which the +error occurred. At the time \fBTcl_BackgroundError\fR is invoked, +\fIinterp->result\fR is expected to contain an error message. +\fBTcl_BackgroundError\fR will invoke the \fBbgerror\fR +Tcl command to report the error in an application-specific fashion. +If no \fBbgerror\fR command exists, or if it returns with an error condition, +then \fBTcl_BackgroundError\fR reports the error itself by printing +a message on the standard error file. +.PP +\fBTcl_BackgroundError\fR does not invoke \fBbgerror\fR immediately +because this could potentially interfere with scripts that are in process +at the time the error occurred. +Instead, it invokes \fBbgerror\fR later as an idle callback. +\fBTcl_BackgroundError\fR saves the values of the \fBerrorInfo\fR and +\fBerrorCode\fR variables and restores these values just before +invoking \fBbgerror\fR. +.PP +It is possible for many background errors to accumulate before +\fBbgerror\fR is invoked. When this happens, each of the errors +is processed in order. However, if \fBbgerror\fR returns a +break exception, then all remaining error reports for the +interpreter are skipped. + +.SH KEYWORDS +background, bgerror, error |