Oracle Coherence for C++ API: ValueChangeEventFilter Class Reference

Detailed Description

Filter which evaluates the content of a MapEvent values based on the specified value extractor.

This filter evaluates to true only for update events that change the value of an extracted attribute.

Example: a filter that evaluates to true if there is an update to an Employee object that changes a value of the LastName property.

ValueChangeEventFilter::create(ReflectionExtractor::create("LastName"));

Author:

djl 2008.05.19

Public Types

typedef spec::Handle

Handle

ValueChangeEventFilter Handle definition.

typedef spec::View

View

ValueChangeEventFilter View definition.

typedef spec::Holder

Holder

ValueChangeEventFilter Holder definition.

Public Member Functions

virtual bool

evaluate (Object::View v) const

Apply the test to the object.

Parameters:

the object to test

Returns:: true if the test passes, false otherwise

virtual bool

equals (Object::View v) const

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 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