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Language Extensions
3.6.3 Anonymous classes, structures and unions
Anonymous classes, structures, and unions are supported as an extension. Anonymous
structures and unions are supported in C and C++.
Anonymous unions are available by default in C++. However, you must specify the
anon_unions pragma if you want to use:
• anonymous unions and structures in C
• anonymous classes and structures in C++.
An anonymous union can be introduced into a containing class by a typedef name.
Unlike a true anonymous union, it does not have to be declared directly. For example:
typedef union
{
int i, j;
} U; // U identifies a reusable anonymous union.
#pragma anon_unions
class A
{
U; // Okay -- references to A::i and A::j are allowed.
};
The extension also enables anonymous classes and anonymous structures, as long as
they have no C++ features. For example, no static data members or member functions,
no non public members, and no nested types (except anonymous classes, structures, or
unions) are allowed in anonymous classes and anonymous structures. For example:
#pragma anon_unions
struct A
{
struct
{
int i, j;
}; // Okay -- references to A::i and A::j are allowed.
};
See also
• Unnamed fields on page 3-31
• #pragma [no_]anon_unions on page 4-49.
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