Value

Object Hierarchy:

Description:

[ CCode ( copy_function = "g_value_copy" , destroy_function = "g_value_unset" , get_value_function = "g_value_get_boxed" , marshaller_type_name = "BOXED" , set_value_function = "g_value_set_boxed" , take_value_function = "g_value_take_boxed" , type_id = "G_TYPE_VALUE" , type_signature = "v" ) ]
public struct Value

An opaque structure used to hold different types of values.

Before it can be used, a `GValue` has to be initialized to a specific type by calling [method@GObject.Value.init] on it.

Many types which are stored within a `GValue` need to allocate data on the heap, so [method@GObject.Value.unset] must always be called on a `GValue` to free any such data once you’re finished with the `GValue`, even if the `GValue` itself is stored on the stack.

The data within the structure has protected scope: it is accessible only to functions within a [struct@GObject.TypeValueTable] structure, or implementations of the `g_value_*()` API. That is, code which implements new fundamental types.

`GValue` users cannot make any assumptions about how data is stored within the 2 element data union, and the g_type member should only be accessed through the [func@GObject.VALUE_TYPE] macro and related macros.

Example: GLib.Value and strings:

public static int main (string[] args) {
	Value value1 = Value (typeof (string));
	value1.set_string ("My string");

	// Output: ``My string``
	print ("%s\n", value1.get_string ());

	// Output: ``My string``
	print ("%s\n", value1.dup_string ());

	// Output: ``My string``
	print ("%s\n", (string) value1);

	// Output: ``My string 2``
	value1 = "My string 2";
	print ("%s\n", (string) value1);

	return 0;
}

valac --pkg gobject-2.0 GLib.Value.vala

Namespace: GLib

Package: gobject-2.0

Content:

Static methods:

public static void register_transform_func (Type src_type, Type dest_type, ValueTransform transform_func)
Registers a value transformation function for use in [method@GObject.
public static bool type_compatible (Type src_type, Type dest_type)
Checks whether a [method@GObject.
public static bool type_transformable (Type src_type, Type dest_type)
Checks whether [method@GObject.

Creation methods:

public Value (Type g_type)
Initializes this to store values of the given type, and sets its value to the initial value for type.

Methods:

public void copy (ref Value dest_value)
Copies the value of this into dest_value.
public void* dup_boxed ()
Get the contents of a g_type_boxed derived Value.
public Object? dup_object ()
Get the contents of a g_type_object derived Value, increasing its reference count.
public ParamSpec dup_param ()
Get the contents of a g_type_param Value, increasing its reference count.
public string? dup_string ()
Get a copy the contents of a g_type_string Value.
public Variant? dup_variant ()
Get the contents of a variant Value, increasing its refcount.
public bool fits_pointer ()
Determines if this will fit inside the size of a pointer value.
public bool get_boolean ()
Get the contents of a g_type_boolean Value.
public void* get_boxed ()
Get the contents of a g_type_boxed derived Value.
public char get_char ()
Do not use this function; it is broken on platforms where the char type is unsigned, such as ARM and PowerPC.
public double get_double ()
Get the contents of a g_type_double Value.
public int get_enum ()
Get the contents of a g_type_enum Value.
public uint get_flags ()
Get the contents of a g_type_flags Value.
public float get_float ()
Get the contents of a g_type_float Value.
public Type get_gtype ()
Get the contents of a g_type_gtype Value.
public int get_int ()
Get the contents of a g_type_int Value.
public int64 get_int64 ()
Get the contents of a g_type_int64 Value.
public long get_long ()
Get the contents of a g_type_long Value.
public unowned Object? get_object ()
Get the contents of a g_type_object derived Value.
public unowned ParamSpec get_param ()
Get the contents of a g_type_param Value.
public void* get_pointer ()
Get the contents of a pointer Value.
public int8 get_schar ()
Get the contents of a g_type_char Value.
public unowned string? get_string ()
Get the contents of a g_type_string Value.
public uchar get_uchar ()
Get the contents of a g_type_uchar Value.
public uint get_uint ()
Get the contents of a g_type_uint Value.
public uint64 get_uint64 ()
Get the contents of a g_type_uint64 Value.
public ulong get_ulong ()
Get the contents of a g_type_ulong Value.
public unowned Variant? get_variant ()
Get the contents of a variant Value.
public bool holds (Type type)
public unowned Value? init (Type g_type)
public void init_from_instance (void* instance)
Initializes and sets this from an instantiatable type.
public void* peek_pointer ()
Returns the value contents as a pointer.
public unowned Value? reset ()
Clears the current value in this and resets it to the initial value (as if the value had just been initialized using [method@GObject.
public void set_boolean (bool v_boolean)
Set the contents of a g_type_boolean Value to v_boolean.
public void set_boxed (void* v_boxed)
Set the contents of a g_type_boxed derived Value to v_boxed.
public void set_char (char v_char)
Set the contents of a g_type_char Value to v_char.
public void set_double (double v_double)
Set the contents of a g_type_double Value to v_double.
public void set_enum (int v_enum)
Set the contents of a g_type_enum Value to v_enum.
public void set_flags (uint v_flags)
Set the contents of a g_type_flags Value to v_flags.
public void set_float (float v_float)
Set the contents of a g_type_float Value to v_float.
public void set_gtype (Type v_gtype)
Set the contents of a g_type_gtype Value to v_gtype.
public void set_instance (void* instance)
Sets this from an instantiatable type.
public void set_int (int v_int)
Set the contents of a g_type_int Value to v_int.
public void set_int64 (int64 v_int64)
Set the contents of a g_type_int64 Value to v_int64.
public void set_interned_string (string? v_string)
Set the contents of a g_type_string Value to v_string.
public void set_long (long v_long)
Set the contents of a g_type_long Value to v_long.
public void set_object (Object? v_object)
Set the contents of a g_type_object derived Value to v_object.
public void set_param (ParamSpec? param)
Set the contents of a g_type_param Value to param.
public void set_param_take_ownership (owned ParamSpec? param)
This is an internal function introduced mainly for C marshallers.
public void set_pointer (void* v_pointer)
Set the contents of a pointer Value to v_pointer.
public void set_schar (int8 v_char)
Set the contents of a g_type_char Value to v_char.
public void set_static_string (string? v_string)
Set the contents of a g_type_string Value to v_string.
public void set_string (string? v_string)
Set the contents of a g_type_string Value to a copy of v_string.
public void set_uchar (uchar v_uchar)
Set the contents of a g_type_uchar Value to v_uchar.
public void set_uint (uint v_uint)
Set the contents of a g_type_uint Value to v_uint.
public void set_uint64 (uint64 v_uint64)
Set the contents of a g_type_uint64 Value to v_uint64.
public void set_ulong (ulong v_ulong)
Set the contents of a g_type_ulong Value to v_ulong.
public void set_variant (Variant? variant)
Set the contents of a variant Value to variant.
public string? steal_string ()
Steal ownership on contents of a g_type_string Value.
public string strdup_contents ()
Return a newly allocated string, which describes the contents of a Value.
public void take_boxed (void* v_boxed)
Sets the contents of a g_type_boxed derived Value to v_boxed and takes over the ownership of the caller’s reference to v_boxed; the caller doesn’t have to unref it any more.
public void take_object (owned Object? v_object)
Sets the contents of a g_type_object derived Value to v_object and takes over the ownership of the caller’s reference to v_object; the caller doesn’t have to unref it any more (i.
public void take_param (owned ParamSpec? param)
Sets the contents of a g_type_param Value to param and takes over the ownership of the caller’s reference to param; the caller doesn’t have to unref it any more.
public void take_string (owned string? v_string)
Sets the contents of a g_type_string Value to v_string.
public void take_variant (owned Variant? variant)
Set the contents of a variant Value to variant, and takes over the ownership of the caller's reference to variant; the caller doesn't have to unref it any more (i.
public bool transform (ref Value dest_value)
Tries to cast the contents of this into a type appropriate to store in dest_value.
public Type type ()
public unowned string type_name ()
public void unset ()
Clears the current value in this (if any) and ‘unsets’ the type.