template union Poco::Placeholder

Overview

ValueHolder union (used by Poco::Any and Poco::Dynamic::Var for small object optimization, when enabled). More…

#include <Any.h>

template <
    typename PlaceholderT,
    unsigned int SizeV = POCO_SMALL_OBJECT_SIZE
    >
union Placeholder
{
    // structs

    struct Size;

    // methods

    void
    erase();

    bool
    isLocal() const;

    void
    setLocal(bool local) const;

    PlaceholderT*
    content() const;
};

Detailed Documentation

ValueHolder union (used by Poco::Any and Poco::Dynamic::Var for small object optimization, when enabled).

If Holder<Type> fits into POCO_SMALL_OBJECT_SIZE bytes of storage, it will be placement-new-allocated into the local buffer (i.e. there will be no heap-allocation). The local buffer size is one byte larger - [POCO_SMALL_OBJECT_SIZE + 1], additional byte value indicating where the object was allocated (0 => heap, 1 => local).