# Class virtual Lwt_engine.select_based

    class virtual select_based : object .. end

Abstract class for engines based on a select-like function.
Inherits

- `Lwt_engine.t`

    method private virtual select : Unix.file_descr list ->
           Unix.file_descr list -> float -> Unix.file_descr list * Unix.file_descr list

`select fds_r fds_w timeout` waits for either:

- one of the file descriptor of `fds_r` to become readable
- one of the file descriptor of `fds_w` to become writable
- timeout to expire

and returns the list of readable file descriptor and the list of writable file descriptors.