Tcl_BackgroundError(3) Tcl (7.5) Tcl_BackgroundError(3)
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NAME
Tcl_BackgroundError - report Tcl error that occurred in
background processing
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_BackgroundError is invoked, interp->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 remaining error reports for the
interpreter are skipped.
KEYWORDS
background, bgerror, error
Page 1 (printed 2/19/99)
