Interface Version Numbers

Querying the versions of the root interfaces

Use iPathEngine::getInterfaceMajorVersion() and iPathEngine::getInterfaceMinorVersion() to obtain a version number for the interface provided by any release of PathEngine.

Use iTestBed::getInterfaceMajorVersion() and iTestBed::getInterfaceMinorVersion() to obtain a version number for the interface provided by any release the testbed.

Note that these 'interface version numbers' are distinct from the major and minor release numbers for the SDK as a whole.
Interface version numbers are purely for managing binary compatibility across the API interface.

Interface changes and backwards compatibility

A release that just includes stuff like bug fixes and optimisation can be made without any change to interface version numbers.

When a public release adds methods to the end of any interface the minor version number relating to that interface is incremented.
This kind of change can be made without breaking binary compatibility between PathEngine and code compiled with old versions of the headers. In this situation executables can continue to run against the new dll, without recompilation.

If any methods are removed from the interface, or if the linkage is changed for any existing method, then the major version number is incremented and the minor version reset to 0.
After this kind of change any code calling the interface must be recompiled.

The PathEngine interface numbers apply to all the interfaces provided by i_pathengine.h.
The TestBed interface numbers apply just to iTestBed.

The following code should be used to check for interface incompatibility before calling any other functions through the interface:

// for an interface to iPathEngine
// check if interfaces are compatible with the headers used for compilation
// pathengine is a pointer to iPathEngine
	if(pathengine->getInterfaceMajorVersion() != PATHENGINE_INTERFACE_MAJOR_VERSION
	 || pathengine->getInterfaceMinorVersion() < PATHENGINE_INTERFACE_MINOR_VERSION
	 )
	{
		//.. report an error - code must be recompiled with new headers
	}
	//.. the interface is compatible with the headers used for compilation

// for an interface to iTestBed
// check if interfaces are compatible with the headers used for compilation
// testbed is a pointer to iTestBed
	if(testbed->getInterfaceMajorVersion() != TESTBED_INTERFACE_MAJOR_VERSION
	 || testbed->getInterfaceMinorVersion() < TESTBED_INTERFACE_MINOR_VERSION
	 )
	{
		//.. report an error - code must be recompiled with new headers
	}
	//.. the interface is compatible with the headers used for compilation

PATHENGINE_INTERFACE_MAJOR_VERSION and PATHENGINE_INTERFACE_MINOR_VERSION are defined in i_pathengine.h.
TESTBED_INTERFACE_MAJOR_VERSION and TESTBED_INTERFACE_MINOR_VERSION are defined in i_testbed.h.