Oracle Coherence for C++ API: Binary Class Reference

Detailed Description

Author:

jh 2008.05.29

Public Types

typedef spec::Handle

Handle

Binary Handle definition.

typedef spec::View

View

Binary View definition.

typedef spec::Holder

Holder

Binary Holder definition.

Public Member Functions

virtual size32_t

hashCode () const

Return a hash code value for the Object.

This method is supported for the benefit of hash-based containers.

The general contract of hashCode is:

Whenever it is invoked on the same Object more than once during an execution of an application, the hashCode method must consistently return the same value, provided no information used in equals comparisons on the object is modified. This value need not remain consistent from one execution of an application to another execution of the same application.
If two Objects are equal according to the equals method, then calling the hashCode method on each of the two Objects must produce the same value.
It is not required that if two Objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct results. However, the programmer should be aware that producing distinct results for unequal objects may improve the performance of hash-based containers.

The default implementation is identity based.

Returns:: a hash code value for this Object

virtual bool

equals (Object::View v) const

virtual bool

isImmutable () const

Return true iff no further changes can be made to the Object, that would effect the outcome of a call to its equals method.

Except for Objects which are naturally immutable (such as String), being immutable generally implies that the Object is only referenced via const pointers or views. Objects which hold references to child Objects, may need to take the immutability of their children into account when determining their own immutability.

This extended check is not performed by the default implementation, but can be integrated into the immutability checks by overriding this method, as well as making use of MemberHandles to reference child Objects.

A typical derived implementation may look as follows:

 bool isImmutable() const
     {
     if (m_fImmutable) // check recorded state
         {
         return true; // already marked as immutable, avoid calculation
         }
     else if (Object::isImmutable()) // ensure shallow immutability
         {
         // ensure deep immutability
         if (m_child1->isImmutable() && m_child2->isImmutable() ...
                                     && m_childN->isImmutable())
             {
             // record and return immutability
             return m_fImmutable = true;
             }
         // some Objects which comprise this Object are still mutable
         }
     return false;
     }

The default implementation return true iff the Object is only referenced via const pointers and or views.

Returns:: true iff the Object is immutable

virtual void

toStream (std::ostream &out) const

Output a human-readable description of this Object to the given stream.

coherence::lang::operator<<(std::ostream, Object::View) is defined and will call into the toStream method, to output Objects. If a managed String object is desired, the COH_TO_STRING macro can be used to build up a String from streamable contents.

 Object::View vKey   = ...
 Object::View vValue = ...
 std::cout << vKey << " = " << vValue << std::endl;

 String::Handle hs = COH_TO_STRING(vKey << " = " << vValue);

Parameters:

out

the stream used to output the description

Protected Member Functions

virtual void

updateLength (size32_t cb)

Allow the length to be modified.

This method is provided for use by OctetArrayWriteBuffer only, and only for read buffers that it owns.

Parameters:

the new length

virtual ReadBuffer::View

instantiateReadBuffer (size32_t of, size32_t cb) const

Factory method: Instantiate a ReadBuffer for a portion of this ReadBuffer.

Parameters:

	of	the beginning index, inclusive
	cb	the number of bytes to include in the resulting ReadBuffer

Returns:: a ReadBuffer that represents a portion of this ReadBuffer