Expression qt.xqcall(qobject, f, ..., handler)
is a thread hopping analogous to the standard \
Lua function xpcall
.
Function f
is invoked with the specified arguments
by the thread owning the Qt object qobject
.
If the execution completes without error,
xqcall
returns true
plus the results returned by f
.
If an error occurs during the execution,
the error handling function handler
is invoked
on the error message in the Qt object thread.
The xqcall
function then returns false
followed by the values returned by the error handler.