# Glib::VariantContainerBase Class Reference
Variant Data Types

The base class from which multiple-item Variants derive, such as Variants containing tuples or arrays. More...

`#include <glibmm/variant.h>`

Inheritance diagram for Glib::VariantContainerBase:
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List of all members.

## Public Types

typedef GVariant* | CType
typedef VariantContainerBase | CppType

## Public Member Functions

| VariantContainerBase ()
| Default constructor.
| VariantContainerBase (GVariant* castitem, bool take_a_reference=false)
| GVariant constructor.
gsize | get_n_children () const
| Determines the number of children in a container Variant instance.
void | get_child (VariantBase& child, gsize index=0) const
| Reads a child item out of this instance.
VariantBase | get_child (gsize index=0)
| Reads a child item out of a container Variant instance.
bool | get_maybe (VariantBase& maybe) const
| If this is a maybe-typed instance, extract its value.

## Static Public Member Functions

static VariantContainerBase | create_tuple (const std::vector< VariantBase >& children)
| Create a tuple variant from a vector of its variant children.
static VariantContainerBase | create_tuple (const VariantBase& child)
| Create a tuple variant with a single variant child.

## Detailed Description

The base class from which multiple-item Variants derive, such as Variants containing tuples or arrays.

Since glibmm 2.28:

## Member Typedef Documentation

typedef VariantContainerBase Glib::VariantContainerBase::CppType

Reimplemented in Glib::Variant< VariantBase >, Glib::Variant< std::vector< T > >, Glib::Variant< std::vector< Glib::ustring > >, Glib::Variant< std::vector< std::string > >, and Glib::Variant< std::map< K, V > >.

typedef GVariant* Glib::VariantContainerBase::CType

Reimplemented in Glib::Variant< VariantBase >.

## Constructor & Destructor Documentation

Glib::VariantContainerBase::VariantContainerBase | ( |  | ) |

Default constructor.

Glib::VariantContainerBase::VariantContainerBase | ( | GVariant * | castitem,
|  | bool | take_a_reference = `false`
| ) |  | `[explicit]`

GVariant constructor.

Parameters:

  castitem | The GVariant to wrap.
  take_a_reference | Whether to take an extra reference of the GVariant or not (not taking one could destroy the GVariant with the wrapper).

## Member Function Documentation

static VariantContainerBase Glib::VariantContainerBase::create_tuple | ( | const std::vector< VariantBase >& | children | ) | `[static]`

Create a tuple variant from a vector of its variant children.

Parameters:

  children | The vector containing the children of the container.

Returns:
  The newly created tuple variant (as a VariantContainerBase).

static VariantContainerBase Glib::VariantContainerBase::create_tuple | ( | const VariantBase& | child | ) | `[static]`

Create a tuple variant with a single variant child.

Parameters:

  child | The child variant.

Returns:
  The newly created tuple variant (as a VariantContainerBase).

VariantBase Glib::VariantContainerBase::get_child | ( | gsize | index = `0` | ) |

Reads a child item out of a container Variant instance.

This includes variants, maybes, arrays, tuples and dictionary entries. It is an error to call this function on any other type of Variant.

It is an error if index is greater than the number of child items in the container. See g_variant_n_children().

This function is O(1).

Since glibmm 2.24:

Parameters:

  index | The index of the child to fetch.

Returns:
  The child at the specified index.

void Glib::VariantContainerBase::get_child | ( | VariantBase& | child,
|  | gsize | index = `0`
| ) |  | const

Reads a child item out of this instance.

This method is valid for variants, maybes, arrays, tuples and dictionary entries.

It is an error if index is greater than the number of child items in the container. See get_n_children().

This function is O(1).

Parameters:

  index | The index of the child to fetch.
  child | A location in which to store the child at the specified index.

Exceptions:

  std::out_of_range |

Since glibmm 2.28:

bool Glib::VariantContainerBase::get_maybe | ( | VariantBase& | maybe | ) | const

If this is a maybe-typed instance, extract its value.

If the value is Nothing, then this function returns `0`.

Parameters:

  maybe | A place in which to return the value (the value may be `0`).

Since glibmm 2.28:

gsize Glib::VariantContainerBase::get_n_children | ( |  | ) | const

Determines the number of children in a container Variant instance.

This includes variants, maybes, arrays, tuples and dictionary entries. It is an error to call this function on any other type of Variant.

For variants, the return value is always 1. For values with maybe types, it is always zero or one. For arrays, it is the length of the array. For tuples it is the number of tuple items (which depends only on the type). For dictionary entries, it is always 2

This function is O(1).

Since glibmm 2.24:

Returns:
  The number of children in the container.