# Class type Ftp_client.ftp_client_pi

    class type ftp_client_pi = object .. end

The client protocol interpreter...

    method exec_e : ?prelim:(ftp_state -> reply -> unit) ->
           cmd -> (ftp_state * reply) Uq_engines.engine

Run another command as engine. The command is first started when the previous command has terminated. The protocol interpreter does not check whether this command is allowed in the current ftp_state or not.

When the command is done, the engine transitions to ``Done(st,r)` where `st` is the state after the command, and `r` is the final reply of the server.

Due to the FTP specification there may be several replies for a command: First, zero or more replies with `cmd_state = `Preliminary`, and then exactly one reply with a final state. The preliminary replies can be intercepted with the `prelim` callback.

    method send_abort : unit -> unit

Sends immediately an `ABOR` command, even when a data transfer is in progress.

TODO - not yet implemented

    method run : unit -> unit

Starts the event system; same as `Unixqueue.run`

    method ftp_state : ftp_state

Returns the current ftp_state

    method state : unit Uq_engines.engine_state

The state in the sense of `Uq_engines`. Possible values are:

- ``Working _`: The control connection is still active. The `int` argument is currently meaningless.
- ``Done()`: The control connection has been terminated.
- ``Error e`: A violation of the FTP protocol happened, or another exception `e` occurred
- ``Aborted`: The `abort` method was called

    method abort : unit -> unit

Shuts any active connection immediately down, and changes the state of the engine to ``Aborted`.

    method event_system : Unixqueue.event_system

The used event system

    method request_notification : (unit -> bool) -> unit

as in `Uq_engines.engine`

    method is_empty : bool

Whether the queue is empty

    method need_ip6 : bool

Whether ``EPSV` or ``EPRT` are required instead of ``PASV` and ``PORT`, respectively. This is first set after connecting to a server (i.e. when the IP address family is known). Before, it is always `false`.

## Feature tests

The following methods are first set when the ``FEAT` command is run. Use `feat_method` to do so. Until then, always `false` is returned.

    method supports_tvfs : bool

Whether TVFS filenames are supported

    method supports_mdtm : bool

Whether the ``MDTM` command is supported. Note that ``MDTM` is sometimes even supported even if the server does not provide the ``FEAT` command to test for this feature.

    method supports_size : bool

Whether the ``SIZE` command is supported. Note that ``SIZE` is sometimes even supported even if the server does not provide the ``FEAT` command to test for this feature.

    method supports_mlst : bool

Whether the ``MLST` and ``MLSD` commands are supported

    method mlst_facts : string list

All available facts for ``MLST` and ``MLSD`

    method mlst_enabled_facts : string list

The enabled facts for ``MLST` and ``MLSD`

    method supports_utf8 : bool

Whether the UTF-8 extension is understood by the server (RFC 2640)