Class: DBus::Object

Inherits:
Object
  • Object
show all
Defined in:
lib/dbus/object.rb

Overview

Exported object type

Exportable D-Bus object class

Objects that are going to be exported by a D-Bus service should inherit from this class. At the client side, use ProxyObject.

Defined Under Namespace

Classes: UndefinedInterface

Constant Summary collapse

@@cur_intf =

Interface

nil
@@intfs_mutex = 
Mutex.new

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ Object

Create a new object with a given path. Use Service#export to export it.



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# File 'lib/dbus/object.rb', line 37

def initialize(path)
  @path = path
  @service = nil
end

Instance Attribute Details

#path ⇒ Object (readonly)

The path of the object.



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# File 'lib/dbus/object.rb', line 23

def path
  @path
end

#service=(value) ⇒ Object (writeonly)

The service that the object is exported by.



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# File 'lib/dbus/object.rb', line 30

def service=(value)
  @service = value
end

Class Method Details

.camelize(str) ⇒ String

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

TODO: borrow a proven implementation

Parameters:

  • str (String)

Returns:

  • (String) 


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# File 'lib/dbus/object.rb', line 338

def self.camelize(str)
  str.split(/_/).map(&:capitalize).join("")
end

.dbus_accessor(ruby_name, type, dbus_name: nil, emits_changed_signal: nil) ⇒ void

This method returns an undefined value.

A read-write property using a pair of reader/writer methods (which must already exist). (To directly access an instance variable, use dbus_attr_accessor instead)

Uses dbus_watcher to set up the PropertiesChanged signal.

Parameters:

  • ruby_name (Symbol) —

    :foo_bar is exposed as FooBar; use dbus_name to override

  • type (Type, SingleCompleteType) —

    a signature like “s” or “a(uus)” or Type::STRING

  • dbus_name (String) (defaults to: nil) —

    if not given it is made by CamelCasing the ruby_name. foo_bar becomes FooBar to convert the Ruby convention to the DBus convention.

  • emits_changed_signal (true, false, :const, :invalidates) (defaults to: nil) —

    see EmitsChangedSignal; if unspecified, ask the interface.

Raises:



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# File 'lib/dbus/object.rb', line 182

def self.dbus_accessor(ruby_name, type, dbus_name: nil, emits_changed_signal: nil)
  raise UndefinedInterface, ruby_name if @@cur_intf.nil?

  dbus_name = make_dbus_name(ruby_name, dbus_name: dbus_name)
  property = Property.new(dbus_name, type, :readwrite, ruby_name: ruby_name)
  @@cur_intf.define(property)

  dbus_watcher(ruby_name, dbus_name: dbus_name, emits_changed_signal: emits_changed_signal)
end

.dbus_attr_accessor(ruby_name, type, dbus_name: nil, emits_changed_signal: nil) ⇒ void

This method returns an undefined value.

A read-write property accessing an instance variable. A combination of ‘attr_accessor` and dbus_accessor.

PropertiesChanged signal will be emitted whenever ‘foo_bar=` is used but not when @foo_bar is written directly.

Parameters:

  • ruby_name (Symbol) —

    :foo_bar is exposed as FooBar; use dbus_name to override

  • type (Type, SingleCompleteType) —

    a signature like “s” or “a(uus)” or Type::STRING

  • dbus_name (String) (defaults to: nil) —

    if not given it is made by CamelCasing the ruby_name. foo_bar becomes FooBar to convert the Ruby convention to the DBus convention.

  • emits_changed_signal (true, false, :const, :invalidates) (defaults to: nil) —

    see EmitsChangedSignal; if unspecified, ask the interface.



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# File 'lib/dbus/object.rb', line 136

def self.dbus_attr_accessor(ruby_name, type, dbus_name: nil, emits_changed_signal: nil)
  attr_accessor(ruby_name)

  dbus_accessor(ruby_name, type, dbus_name: dbus_name, emits_changed_signal: emits_changed_signal)
end

.dbus_attr_reader(ruby_name, type, dbus_name: nil, emits_changed_signal: nil) ⇒ void

This method returns an undefined value.

A read-only property accessing an instance variable. A combination of ‘attr_reader` and dbus_reader.

Whenever the property value gets changed from “inside” the object, you should emit the ‘PropertiesChanged` signal by calling #dbus_properties_changed.

dbus_properties_changed(interface_name, {dbus_name.to_s => value}, [])

or, omitting the value in the signal,

dbus_properties_changed(interface_name, {}, [dbus_name.to_s])

Parameters:

  • ruby_name (Symbol) —

    :foo_bar is exposed as FooBar; use dbus_name to override

  • type (Type, SingleCompleteType) —

    a signature like “s” or “a(uus)” or Type::STRING

  • dbus_name (String) (defaults to: nil) —

    if not given it is made by CamelCasing the ruby_name. foo_bar becomes FooBar to convert the Ruby convention to the DBus convention.

  • emits_changed_signal (true, false, :const, :invalidates) (defaults to: nil) —

    see EmitsChangedSignal; if unspecified, ask the interface.



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# File 'lib/dbus/object.rb', line 157

def self.dbus_attr_reader(ruby_name, type, dbus_name: nil, emits_changed_signal: nil)
  attr_reader(ruby_name)

  dbus_reader(ruby_name, type, dbus_name: dbus_name, emits_changed_signal: emits_changed_signal)
end

.dbus_attr_writer(ruby_name, type, dbus_name: nil, emits_changed_signal: nil) ⇒ void

This method returns an undefined value.

A write-only property accessing an instance variable. A combination of ‘attr_writer` and dbus_writer.

Parameters:

  • ruby_name (Symbol) —

    :foo_bar is exposed as FooBar; use dbus_name to override

  • type (Type, SingleCompleteType) —

    a signature like “s” or “a(uus)” or Type::STRING

  • dbus_name (String) (defaults to: nil) —

    if not given it is made by CamelCasing the ruby_name. foo_bar becomes FooBar to convert the Ruby convention to the DBus convention.

  • emits_changed_signal (true, false, :const, :invalidates) (defaults to: nil) —

    see EmitsChangedSignal; if unspecified, ask the interface.



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# File 'lib/dbus/object.rb', line 168

def self.dbus_attr_writer(ruby_name, type, dbus_name: nil, emits_changed_signal: nil)
  attr_writer(ruby_name)

  dbus_writer(ruby_name, type, dbus_name: dbus_name, emits_changed_signal: emits_changed_signal)
end

.dbus_interface(name) ⇒ Object

Select (and create) the interface that the following defined methods belong to.

Parameters:

  • name (String) —

    interface name like “org.example.ManagerManager”

See Also:



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# File 'lib/dbus/object.rb', line 80

def self.dbus_interface(name)
  @@intfs_mutex.synchronize do
    @@cur_intf = intfs[name]
    if !@@cur_intf
      @@cur_intf = Interface.new(name) # validates the name
      # As this is a mutable class_attr, we cannot use
      #   self.intfs[name] = @@cur_intf                      # Hash#[]=
      # as that would modify parent class attr in place.
      # Using the setter lets a subclass have the new value
      # while the superclass keeps the old one.
      self.intfs = intfs.merge(name => @@cur_intf)
    end
    begin
      yield
    ensure
      @@cur_intf = nil
    end
  end
end

.dbus_method(sym, prototype = "", &block) ⇒ Object

Defines an exportable method on the object with the given name sym, prototype and the code in a block.

Parameters:

Raises:



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# File 'lib/dbus/object.rb', line 294

def self.dbus_method(sym, prototype = "", &block)
  raise UndefinedInterface, sym if @@cur_intf.nil?

  @@cur_intf.define(Method.new(sym.to_s).from_prototype(prototype))

  ruby_name = Object.make_method_name(@@cur_intf.name, sym.to_s)
  # ::Module#define_method(name) { body }
  define_method(ruby_name, &block)
end

.dbus_reader(ruby_name, type, dbus_name: nil, emits_changed_signal: nil) ⇒ void

This method returns an undefined value.

A read-only property accessing a reader method (which must already exist). (To directly access an instance variable, use dbus_attr_reader instead)

At the D-Bus side the property is read only but it makes perfect sense to implement it with a read-write attr_accessor. In that case this method uses dbus_watcher to set up the PropertiesChanged signal.

attr_accessor :foo_bar
dbus_reader :foo_bar, "s"

If the property value should change by other means than its attr_writer, you should emit the ‘PropertiesChanged` signal by calling #dbus_properties_changed.

dbus_properties_changed(interface_name, {dbus_name.to_s => value}, [])

or, omitting the value in the signal,

dbus_properties_changed(interface_name, {}, [dbus_name.to_s])

Parameters:

  • ruby_name (Symbol) —

    :foo_bar is exposed as FooBar; use dbus_name to override

  • type (Type, SingleCompleteType) —

    a signature like “s” or “a(uus)” or Type::STRING

  • dbus_name (String) (defaults to: nil) —

    if not given it is made by CamelCasing the ruby_name. foo_bar becomes FooBar to convert the Ruby convention to the DBus convention.

  • emits_changed_signal (true, false, :const, :invalidates) (defaults to: nil) —

    see EmitsChangedSignal; if unspecified, ask the interface.

Raises:



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# File 'lib/dbus/object.rb', line 214

def self.dbus_reader(ruby_name, type, dbus_name: nil, emits_changed_signal: nil)
  raise UndefinedInterface, ruby_name if @@cur_intf.nil?

  dbus_name = make_dbus_name(ruby_name, dbus_name: dbus_name)
  property = Property.new(dbus_name, type, :read, ruby_name: ruby_name)
  @@cur_intf.define(property)

  ruby_name_eq = "#{ruby_name}=".to_sym
  return unless method_defined?(ruby_name_eq)

  dbus_watcher(ruby_name, dbus_name: dbus_name, emits_changed_signal: emits_changed_signal)
end

.dbus_signal(sym, prototype = "") ⇒ Object

Defines a signal for the object with a given name sym and prototype.

Raises:



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# File 'lib/dbus/object.rb', line 314

def self.dbus_signal(sym, prototype = "")
  raise UndefinedInterface, sym if @@cur_intf.nil?

  cur_intf = @@cur_intf
  signal = Signal.new(sym.to_s).from_prototype(prototype)
  cur_intf.define(Signal.new(sym.to_s).from_prototype(prototype))

  # ::Module#define_method(name) { body }
  define_method(sym.to_s) do |*args|
    emit(cur_intf, signal, *args)
  end
end

.dbus_watcher(ruby_name, dbus_name: nil, emits_changed_signal: nil) ⇒ void

This method returns an undefined value.

Enables automatic sending of the PropertiesChanged signal. For ruby_name ‘foo_bar`, wrap `foo_bar=` so that it sends the signal for FooBar. The original version remains as `_original_foo_bar=`.

Parameters:

  • ruby_name (Symbol) —

    :foo_bar and :foo_bar= both mean the same thing

  • dbus_name (String) (defaults to: nil) —

    if not given it is made by CamelCasing the ruby_name. foo_bar becomes FooBar to convert the Ruby convention to the DBus convention.

  • emits_changed_signal (true, false, :const, :invalidates) (defaults to: nil) —

    see EmitsChangedSignal; if unspecified, ask the interface.

Raises:



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# File 'lib/dbus/object.rb', line 256

def self.dbus_watcher(ruby_name, dbus_name: nil, emits_changed_signal: nil)
  raise UndefinedInterface, ruby_name if @@cur_intf.nil?

  interface_name = @@cur_intf.name

  ruby_name = ruby_name.to_s.sub(/=$/, "").to_sym
  ruby_name_eq = "#{ruby_name}=".to_sym
  original_ruby_name_eq = "_original_#{ruby_name_eq}"

  dbus_name = make_dbus_name(ruby_name, dbus_name: dbus_name)

  emits_changed_signal = EmitsChangedSignal.new(emits_changed_signal, interface: @@cur_intf)

  # the argument order is alias_method(new_name, existing_name)
  alias_method original_ruby_name_eq, ruby_name_eq
  define_method ruby_name_eq do |value|
    result = public_send(original_ruby_name_eq, value)

    case emits_changed_signal.value
    when true
      # signature: "interface:s, changed_props:a{sv}, invalidated_props:as"
      dbus_properties_changed(interface_name, { dbus_name.to_s => value }, [])
    when :invalidates
      dbus_properties_changed(interface_name, {}, [dbus_name.to_s])
    when :const
      # Oh my, seeing a value change of a supposedly constant property.
      # Maybe should have raised at declaration time, don't make a fuss now.
    when false
      # Do nothing
    end

    result
  end
end

.dbus_writer(ruby_name, type, dbus_name: nil, emits_changed_signal: nil) ⇒ void

This method returns an undefined value.

A write-only property accessing a writer method (which must already exist). (To directly access an instance variable, use dbus_attr_writer instead)

Uses dbus_watcher to set up the PropertiesChanged signal.

Parameters:

  • ruby_name (Symbol) —

    :foo_bar is exposed as FooBar; use dbus_name to override

  • type (Type, SingleCompleteType) —

    a signature like “s” or “a(uus)” or Type::STRING

  • dbus_name (String) (defaults to: nil) —

    if not given it is made by CamelCasing the ruby_name. foo_bar becomes FooBar to convert the Ruby convention to the DBus convention.

  • emits_changed_signal (true, false, :const, :invalidates) (defaults to: nil) —

    see EmitsChangedSignal; if unspecified, ask the interface.

Raises:



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# File 'lib/dbus/object.rb', line 234

def self.dbus_writer(ruby_name, type, dbus_name: nil, emits_changed_signal: nil)
  raise UndefinedInterface, ruby_name if @@cur_intf.nil?

  dbus_name = make_dbus_name(ruby_name, dbus_name: dbus_name)
  property = Property.new(dbus_name, type, :write, ruby_name: ruby_name)
  @@cur_intf.define(property)

  dbus_watcher(ruby_name, dbus_name: dbus_name, emits_changed_signal: emits_changed_signal)
end

.emits_changed_signal=(value) ⇒ Object

Declare the behavior of PropertiesChanged signal, common for all properties in this interface (individual properties may override it)

Examples:

self.emits_changed_signal = :invalidates

Parameters:

  • value (true, false, :const, :invalidates)

Raises:



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# File 'lib/dbus/object.rb', line 114

def self.emits_changed_signal=(value)
  raise UndefinedInterface, :emits_changed_signal if @@cur_intf.nil?

  @@cur_intf.emits_changed_signal = EmitsChangedSignal.new(value)
end

.make_dbus_name(ruby_name, dbus_name: nil) ⇒ Symbol

Make a D-Bus conventional name, CamelCased.

Parameters:

  • ruby_name (String, Symbol) —

    eg :do_something

  • dbus_name (String, Symbol, nil) (defaults to: nil) —

    use this if given

Returns:

  • (Symbol) —

    eg DoSomething



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# File 'lib/dbus/object.rb', line 346

def self.make_dbus_name(ruby_name, dbus_name: nil)
  dbus_name ||= camelize(ruby_name.to_s)
  dbus_name.to_sym
end

.make_method_name(intfname, methname) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Helper method that returns a method name generated from the interface name intfname and method name methname.



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# File 'lib/dbus/object.rb', line 330

def self.make_method_name(intfname, methname)
  "#{intfname}%%#{methname}"
end

Instance Method Details

#dbus_lookup_property(interface_name, property_name) ⇒ Property

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Parameters:

  • interface_name (String)
  • property_name (String)

Returns:

Raises:



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# File 'lib/dbus/object.rb', line 375

def dbus_lookup_property(interface_name, property_name)
  # what should happen for unknown properties
  # plasma: InvalidArgs (propname), UnknownInterface (interface)
  # systemd: UnknownProperty
  interface = intfs[interface_name]
  if !interface
    raise DBus.error("org.freedesktop.DBus.Error.UnknownProperty"),
          "Property '#{interface_name}.#{property_name}' (on object '#{@path}') not found: no such interface"
  end

  property = interface.properties[property_name.to_sym]
  if !property
    raise DBus.error("org.freedesktop.DBus.Error.UnknownProperty"),
          "Property '#{interface_name}.#{property_name}' (on object '#{@path}') not found"
  end

  property
end

#dbus_properties_changed(interface_name, changed_props, invalidated_props) ⇒ Object

Use this instead of calling PropertiesChanged directly. This one considers not only the PC signature (which says that all property values are variants) but also the specific property type.

Parameters:

  • interface_name (String) —

    interface name like “org.example.ManagerManager”

  • changed_props (Hash{String => ::Object}) —

    changed properties (D-Bus names) and their values.

  • invalidated_props (Array<String>) —

    names of properties whose changed value is not specified



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# File 'lib/dbus/object.rb', line 359

def dbus_properties_changed(interface_name, changed_props, invalidated_props)
  typed_changed_props = changed_props.map do |dbus_name, value|
    property = dbus_lookup_property(interface_name, dbus_name)
    type = property.type
    typed_value = Data.make_typed(type, value)
    variant = Data::Variant.new(typed_value, member_type: type)
    [dbus_name, variant]
  end.to_h
  PropertiesChanged(interface_name, typed_changed_props, invalidated_props)
end

#dispatch(msg) ⇒ Object

Dispatch a message msg to call exported methods



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# File 'lib/dbus/object.rb', line 43

def dispatch(msg)
  case msg.message_type
  when Message::METHOD_CALL
    reply = nil
    begin
      iface = intfs[msg.interface]
      if !iface
        raise DBus.error("org.freedesktop.DBus.Error.UnknownMethod"),
              "Interface \"#{msg.interface}\" of object \"#{msg.path}\" doesn't exist"
      end
      member_sym = msg.member.to_sym
      meth = iface.methods[member_sym]
      if !meth
        raise DBus.error("org.freedesktop.DBus.Error.UnknownMethod"),
              "Method \"#{msg.member}\" on interface \"#{msg.interface}\" of object \"#{msg.path}\" doesn't exist"
      end
      methname = Object.make_method_name(msg.interface, msg.member)
      retdata = method(methname).call(*msg.params)
      retdata = [*retdata]

      reply = Message.method_return(msg)
      rsigs = meth.rets.map(&:type)
      rsigs.zip(retdata).each do |rsig, rdata|
        reply.add_param(rsig, rdata)
      end
    rescue StandardError => e
      dbus_msg_exc = msg.annotate_exception(e)
      reply = ErrorMessage.from_exception(dbus_msg_exc).reply_to(msg)
    end
    @service.bus.message_queue.push(reply)
  end
end

#emit(intf, sig, *args) ⇒ Object

Emits a signal from the object with the given interface, signal sig and arguments args.

Parameters:



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# File 'lib/dbus/object.rb', line 309

def emit(intf, sig, *args)
  @service.bus.emit(@service, self, intf, sig, *args)
end

#interfaces_and_properties ⇒ Hash{String => Hash{String => Data::Base}}

Generates information about interfaces and properties of the object

Returns a hash containing interfaces names as keys. Each value is the same hash that would be returned by the org.freedesktop.DBus.Properties.GetAll() method for that combination of object path and interface. If an interface has no properties, the empty hash is returned.

Returns:

  • (Hash{String => Hash{String => Data::Base}}) —

    interface -> property -> value



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# File 'lib/dbus/object.rb', line 403

def interfaces_and_properties
  get_all_method = self.class.make_method_name("org.freedesktop.DBus.Properties", :GetAll)

  intfs.keys.each_with_object({}) do |interface, hash|
    hash[interface] = public_send(get_all_method, interface).first
  end
end