# Class Netchannels.input_filter

    class input_filter : in_obj_channel -> io_obj_channel -> in_obj_channel

An `input_filter` filters the data read from it through the `io_obj_channel` (usually a `pipe` after the data have been retrieved from the passed `in_obj_channel`.

An `input_filter` object never generates `Buffer_underrun` exceptions. However, if the passed `in_obj_channel` or `io_obj_channel` raises such an exception, the exception will fall through the calling chain.

If the filter is closed, the `io_obj_channel` will be closed, too, but not the source `in_obj_channel` (so you can still read further data from it).