output_handler
handles the results of evaluate
,
including the values, graphics, conditions. Each type of output is handled by
a particular function in the handler object.new_output_handler(source = identity, text = identity, graphics = identity,
message = identity, warning = identity, error = identity, value = render)
recordPlot
.message
output.warning
output.stop
output.output_handler
objectvalue
handler, where a visible return value is saved in the output
list.Calling the constructor with no arguments results in the default handler, which mimics the behavior of the console by printing visible values.
Note that recursion is common: for example, if value
does any
printing, then the text
or graphics
handlers may be called.