Determines the first item type of a tuple or dictionary entry
type.
This function may only be used with tuple or dictionary entry types,
but must not be used with the generic tuple type
G_VARIANT_TYPE_TUPLE.
In the case of a dictionary entry type, this returns the type of
the key.
NULL is returned in case of type being G_VARIANT_TYPE_UNIT.
This call, together with g_variant_type_next() provides an iterator
interface over tuple and dictionary entry types.
Since 2.24. [transfer none]
Determines the first item type of a tuple or dictionary entry type. This function may only be used with tuple or dictionary entry types, but must not be used with the generic tuple type G_VARIANT_TYPE_TUPLE. In the case of a dictionary entry type, this returns the type of the key. NULL is returned in case of type being G_VARIANT_TYPE_UNIT. This call, together with g_variant_type_next() provides an iterator interface over tuple and dictionary entry types. Since 2.24. [transfer none]