Tcl_BackgroundError(3) Tcl Library Procedures Tcl_BackgroundError(3) ______________________________________________________________________________
NAME
Tcl_BackgroundError - report Tcl error that occurred in background pro-
cessing
SYNOPSIS
#include <tcl.h>
Tcl_BackgroundError(interp)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter in which the error
occurred.
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DESCRIPTION
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 Tcl_BackgroundError with an interp argument identifying the
interpreter in which the error occurred. At the time Tcl_BackgroundEr-
ror is invoked, the interpreter's result is expected to contain an
error message. Tcl_BackgroundError will invoke the bgerror Tcl command
to report the error in an application-specific fashion. If no bgerror
command exists, or if it returns with an error condition, then
Tcl_BackgroundError reports the error itself by printing a message on
the standard error file.
Tcl_BackgroundError does not invoke bgerror immediately because this
could potentially interfere with scripts that are in process at the
time the error occurred. Instead, it invokes bgerror later as an idle
callback. Tcl_BackgroundError saves the values of the errorInfo and
errorCode variables and restores these values just before invoking
bgerror.
It is possible for many background errors to accumulate before bgerror
is invoked. When this happens, each of the errors is processed in
order. However, if bgerror returns a break exception, then all remain-
ing error reports for the interpreter are skipped.
KEYWORDS
background, bgerror, error
Tcl 7.5 Tcl_BackgroundError(3)
Mac OS X 10.5 - Generated Sun Oct 28 21:08:43 EDT 2007