# create the manager
h <- taskCallbackManager()
# add a callback
h$add(function(expr, value, ok, visible) {
cat("In handler\n")
return(TRUE)
}, name = "simpleHandler")
# look at the internal callbacks.
getTaskCallbackNames()
# look at the R-level callbacks
names(h$callbacks())
getTaskCallbackNames()
removeTaskCallback("R-taskCallbackManager")
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