Glib::Property< T > Class Template Reference

A Glib::Object property. More...

#include <glibmm/property.h>

Inheritance diagram for Glib::Property< T >:

Public Types
using	PropertyType = T
using	ValueType = Glib::Value< T >

Public Member Functions
	Property (Glib::Object &object, const Glib::ustring & name)
	Constructs a property of the object with the specified name.
	Property (Glib::Object &object, const Glib::ustring & name, const PropertyType &default_value)
	Constructs a property of the object with the specified name and default_value.
	Property (Glib::Object &object, const Glib::ustring & name, const Glib::ustring &nick, const Glib::ustring &blurb, Glib::ParamFlags flags)
	Constructs a property of the object with the specified name, nick, blurb and flags.
	Property (Glib::Object &object, const Glib::ustring & name, const PropertyType &default_value, const Glib::ustring &nick, const Glib::ustring &blurb, Glib::ParamFlags flags)
	Constructs a property of the object with the specified name, default_value, nick, blurb and flags.
void	set_value (const PropertyType &data)
	Sets the value of the property to data.
PropertyType	get_value () const
	Returns the value of the property.
Property< T > &	operator= (const PropertyType &data)
	Sets the value of the property to data.
	operator PropertyType () const
	Returns the value of the property.
Glib::PropertyProxy< T >	get_proxy ()
	Returns a proxy object that can be used to read or write this property.
Glib::PropertyProxy_ReadOnly< T >	get_proxy () const
	Returns a proxy object that can be used to read this property.
Public Member Functions inherited from Glib::PropertyBase
	PropertyBase (const PropertyBase &)=delete
PropertyBase &	operator= (const PropertyBase &)=delete
Glib::ustring	get_name () const
	Returns the name of the property.
Glib::ustring	get_nick () const
	Returns the nickname of the property.
Glib::ustring	get_blurb () const
	Returns the short description of the property.
void	notify ()
	Notifies the object containing the property that the property has changed.

Additional Inherited Members
Protected Member Functions inherited from Glib::PropertyBase
	PropertyBase (Glib::Object &object, GType value_type)
	This constructs a property of type value_type for the object.
	~PropertyBase () noexcept
bool	lookup_property (const Glib::ustring & name)
	Checks if the property has already been installed.
void	install_property (GParamSpec *param_spec)
	Installs the property specified by the given param_spec.
const char *	get_name_internal () const
	Returns the name of the property.
Protected Attributes inherited from Glib::PropertyBase
Glib::Object *	object_
Glib::ValueBase	value_
GParamSpec *	param_spec_

Detailed Description

template<class T>
class Glib::Property< T >

A Glib::Object property.

This class wraps a GObject property, providing a C++ API to the GObject property system, for use with classes derived from Glib::Object or Glib::Interface.

A property is a value associated with each instance of a type and some class data for each property:

• Its unique name, used to identify the property.
• A human-readable nick name.
• A short description.
• The default value and the minimum and maximum bounds (depending on the type of the property).
• Flags, defining, among other things, whether the property can be read or written.

This Property class currently supports the name, nick name, description, default value and flags. The minimum and maximum bounds are set to the full range of the value. Because of internal implementation, flags shouldn't be set to values: Glib::ParamFlags::STATIC_NAME, Glib::ParamFlags::STATIC_NICK, Glib::ParamFlags::STATIC_BLURB, Glib::ParamFlags::CONSTRUCT and Glib::ParamFlags::CONSTRUCT_ONLY.

The class information must be installed into the GObject system once per property, but this is handled automatically.

Each property belongs to an object, inheriting from Glib::Object. A reference to the object must be passed to the constructor of the property.

Each instance of a Glib::Object-derived type must construct the same properties (same type, same name) in the same order. One way to achieve this is to declare all properties as direct data members of the type.

You may register new properties for your class (actually for the underlying GType) simply by adding a Property instance as a class member. However, your constructor must call the Glib::ObjectBase constructor with a new GType name, in order to register a new GType.

Example:

class MyCellRenderer : public Gtk::CellRenderer
{
public:
  MyCellRenderer()
  :
  Glib::ObjectBase (typeid(MyCellRenderer)),
  Gtk::CellRenderer(),
  property_mybool  (*this, "mybool", true),
  property_myint_  (*this, "myint",    42)
  {}
 
  virtual ~MyCellRenderer() {}
 
  // Glib::Property<> can be public,
  Glib::Property<bool> property_mybool;
  // or private, and combined with Glib::PropertyProxy<>.
  Glib::PropertyProxy<int> property_myint() { return property_myint_.get_proxy(); }
  Glib::PropertyProxy_ReadOnly<int> property_myint() const { return property_myint_.get_proxy(); }
 
private:
  Glib::Property<int> property_myint_;
};

Glib::Property and Gtk::Builder

The new GType is registered, and the properties installed in the GType, when the first instance of the class is created. When the underlying GObject-derived instance is created before the wrapping Glib::Object-derived instance, you may have to first create a dummy instance just to register the GType. See the description of Gtk::Builder for instructions how to combine Property with Gtk::Builder.

Member Typedef Documentation

PropertyType

template <class T >

using Glib::Property< T >::PropertyType = T

ValueType

template <class T >

using Glib::Property< T >::ValueType = Glib::Value<T>

Constructor & Destructor Documentation

Property() [1/4]

template <class T >

Glib::Property< T >::Property	(	Glib::Object &	object,
		const Glib::ustring &	name
	)

Constructs a property of the object with the specified name.

For each instance of the object, the same property must be constructed with the same name.

Property() [2/4]

template <class T >

Glib::Property< T >::Property	(	Glib::Object &	object,
		const Glib::ustring &	name,
		const PropertyType &	default_value
	)

Constructs a property of the object with the specified name and default_value.

For each instance of the object, the same property must be constructed with the same name.

Property() [3/4]

template <class T >

Glib::Property< T >::Property	(	Glib::Object &	object,
		const Glib::ustring &	name,
		const Glib::ustring &	nick,
		const Glib::ustring &	blurb,
		Glib::ParamFlags	flags
	)

Constructs a property of the object with the specified name, nick, blurb and flags.

For each instance of the object, the same property must be constructed with the same name.

Property() [4/4]

template <class T >

Glib::Property< T >::Property	(	Glib::Object &	object,
		const Glib::ustring &	name,
		const PropertyType &	default_value,
		const Glib::ustring &	nick,
		const Glib::ustring &	blurb,
		Glib::ParamFlags	flags
	)

Constructs a property of the object with the specified name, default_value, nick, blurb and flags.

For each instance of the object, the same property must be constructed with the same name.

Member Function Documentation

get_proxy() [1/2]

template <class T >

Glib::PropertyProxy< T > Glib::Property< T >::get_proxy ( )

inline

Returns a proxy object that can be used to read or write this property.

get_proxy() [2/2]

template <class T >

Glib::PropertyProxy_ReadOnly< T > Glib::Property< T >::get_proxy ( ) const

inline

Returns a proxy object that can be used to read this property.

get_value()

template <class T >

PropertyType Glib::Property< T >::get_value ( ) const

inline

Returns the value of the property.

operator PropertyType()

template <class T >

Glib::Property< T >::operator PropertyType ( ) const

inline

Returns the value of the property.

operator=()

template <class T >

Property< T > & Glib::Property< T >::operator= ( const PropertyType &  data )

inline

Sets the value of the property to data.

The object containing the property will be notified about the change.

set_value()

template <class T >

void Glib::Property< T >::set_value ( const PropertyType &  data )

inline

Sets the value of the property to data.

The object containing the property will be notified about the change.