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docs/gobject/tutorial: Use g_object_class_install_properties
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@ -495,14 +495,14 @@ void g_object_run_dispose (GObject *object);
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One of GObject's nice features is its generic get/set mechanism for object
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properties. When an object
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is instantiated, the object's class_init handler should be used to register
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the object's properties with <function><link linkend="g-object-class-install-property">g_object_class_install_property</link></function>
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the object's properties with <function><link linkend="g-object-class-install-properties">g_object_class_install_properties</link></function>
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(implemented in <filename>gobject.c</filename>).
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</para>
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<para>
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The best way to understand how object properties work is by looking at a real example
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on how it is used:
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<programlisting>
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<informalexample><programlisting>
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/************************************************/
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/* Implementation */
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/************************************************/
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@ -512,9 +512,13 @@ enum
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PROP_0,
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PROP_MAMAN_NAME,
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PROP_PAPA_NUMBER
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PROP_PAPA_NUMBER,
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N_PROPERTIES
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};
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static GParamSpec *obj_properties[N_PROPERTIES] = { NULL, };
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static void
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maman_bar_set_property (GObject *object,
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guint property_id,
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@ -572,30 +576,29 @@ static void
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maman_bar_class_init (MamanBarClass *klass)
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
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GParamSpec *pspec;
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gobject_class->set_property = maman_bar_set_property;
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gobject_class->get_property = maman_bar_get_property;
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pspec = g_param_spec_string ("maman-name",
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obj_properties[PROP_NAME] =
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g_param_spec_string ("maman-name",
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"Maman construct prop",
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"Set maman's name",
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"no-name-set" /* default value */,
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G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE);
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g_object_class_install_property (gobject_class,
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PROP_MAMAN_NAME,
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pspec);
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pspec = g_param_spec_uchar ("papa-number",
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obj_properties[PROP_NUMBER] =
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g_param_spec_uchar ("papa-number",
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"Number of current Papa",
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"Set/Get papa's number",
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0 /* minimum value */,
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10 /* maximum value */,
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2 /* default value */,
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G_PARAM_READWRITE);
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g_object_class_install_property (gobject_class,
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PROP_PAPA_NUMBER,
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pspec);
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g_object_class_install_properties (gobject_class,
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N_PROPERTIES,
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obj_properties);
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}
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/************************************************/
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@ -613,7 +616,7 @@ g_value_set_char (&val, 11);
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g_object_set_property (G_OBJECT (bar), "papa-number", &val);
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g_value_unset (&val);
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</programlisting>
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</programlisting></informalexample>
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The client code just above looks simple but a lot of things happen under the hood:
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</para>
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@ -341,26 +341,37 @@ maman_bar_init (MamanBar *self)
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<xref linkend="gobject-properties"/>. Make sure that these properties use a construct only
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<link linkend="GParamSpec"><type>GParamSpec</type></link> by setting the param spec's flag field to G_PARAM_CONSTRUCT_ONLY: this helps
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GType ensure that these properties are not set again later by malicious user code.
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<programlisting>
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<informalexample><programlisting>
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enum {
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PROP_0,
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PROP_MAMAN,
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N_PROPERTIES
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};
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static GParamSpec *obj_properties[N_PROPERTIES] = { NULL, };
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static void
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bar_class_init (MamanBarClass *klass)
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
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GParamSpec *pspec;
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gobject_class->set_property = bar_set_property;
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gobject_class->get_property = bar_get_property;
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pspec = g_param_spec_string ("maman",
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obj_properties[PROP_MAMAN] =
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g_param_spec_string ("maman",
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"Maman construct prop",
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"Set maman's name",
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"no-name-set" /* default value */,
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G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE);
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g_object_class_install_property (gobject_class,
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PROP_MAMAN,
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pspec);
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g_object_class_install_properties (gobject_class,
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N_PROPERTIES,
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obj_properties);
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}
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</programlisting>
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</programlisting></informalexample>
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If you need this, make sure you can build and run code similar to the code shown above. Make sure
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your construct properties can set correctly during construction, make sure you cannot set them
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afterwards and make sure that if your users do not call <function><link linkend="g-object-new">g_object_new</link></function>
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