# Module OBus_signal

    module OBus_signal: sig .. end

D-Bus signals

###### Emitting signals

    val emit : 'a OBus_member.Signal.t ->
           'b OBus_object.t -> ?peer:OBus_peer.t -> 'a -> unit Lwt.t

`emit signal obj ?peer args` emit `signal` from `obj`. The destinations of the signal are selected as follow:

- if `peer` is provided, then the message is sent only to it
- otherwise, if the the object has an owner, it is sent to the owner,
- otherwise, the message is broadcasted on all the connection `obj` is exported.

###### Receving signals

    type 'a t

Type of a signal descriptor. A signal descriptor represent the source of a signal and describe how the value should be transformed.

    val make : 'a OBus_member.Signal.t -> OBus_proxy.t -> 'a t

`make signal proxy` creates a signal descriptor.

    val make_any : 'a OBus_member.Signal.t -> OBus_peer.t -> (OBus_proxy.t * 'a) t

`make_any signal peer` creates a signal descriptor for receiving signals from any object of `peer`.

    val connect : ?switch:Lwt_switch.t -> 'a t -> 'a React.event Lwt.t

`connect ?switch sd` connects the signal descriptor `sd` and returns the event which occurs when the given D-Bus signal is received.

###### Signals transformations and parameters

    val map_event : ((OBus_context.t * 'a) React.event -> (OBus_context.t * 'b) React.event) ->
           'a t -> 'b t

`map_event f sd` transforms with `f` the event that is created when `sd` is connected.

    val map : ('a -> 'b) -> 'a t -> 'b t

Simplified version of `OBus_signal.map_event`.

    val map_with_context : (OBus_context.t -> 'a -> 'b) -> 'a t -> 'b t

Same as `OBus_signal.map` but the mapping function also receive the context.

    val with_context : 'a t -> (OBus_context.t * 'a) t

Returns a signal descriptor that returns contexts in which signals are received.

    val with_filters : OBus_match.arguments -> 'a t -> 'a t

`with_filters filters sd` is the signal descriptor `sd` with the given list of argument filters. When connected, obus will add this filters to the matching rule send to the message bus, so the bus can use them to drop messages that do not match these filters.

The goal of argument filters is to reduce the number of messages received, and so to reduce the number of wakeup of the program.

Note that match rule management must be activated for filters to take effect (see `OBus_signal.with_match_rule`).

    val with_match_rule : bool -> 'a t -> 'a t

`with_match_rule state sd` enables or disables the automatic management of matching rules. If the endpoint of the underlying connection is a message bus it defaults to `true`, otherwise it default to `false`.