-- File:	Standard_ErrorHandlerCallback.cdl
-- Created:	Thu Apr 13 11:17:05 2006
-- Author:	Andrey BETENEV
---Copyright:	Open CASCADE SAS 2006

deferred class ErrorHandlerCallback from Standard

    ---Purpose: Defines a base class for callback objects that can be registered
    --          in the OCC error handler (the class simulating C++ exceptions)
    --          so as to be correctly destroyed when error handler is activated.
    --
    --          Note that this is needed only when Open CASCADE is compiled with
    --          NO_CXX_EXCEPTION or OCC_CONVERT_SIGNALS options (i.e. on UNIX/Linux).
    --          In that case, raising OCC exception and/or signal will not cause 
    --          C++ stack unwinding and destruction of objects created in the stack.
    --
    --          This class is intended to protect critical objects and operations in 
    --          the try {} catch {} block from being bypassed by OCC signal or exception.
    --
    --          Inherit your object from that class, implement DestroyCallback() function,
    --          and call Register/Unregister in critical points.
    --
    --          Note that you must ensure that your object has life span longer than 
    --          that of the try {} block in which it calls Register().

is

    Initialize returns ErrorHandlerCallback;
    	---Purpose: Empty constructor
	---C++: inline
	
    RegisterCallback (me: in out);
    	---Purpose: Registers this callback object in the current error handler 
	--          (if found).
	---C++: inline
	
    UnregisterCallback (me: in out);
    	---Purpose: Unregisters this callback object from the error handler.
	---C++: inline
	---C++: alias "virtual Standard_EXPORT ~Standard_ErrorHandlerCallback ();"

    DestroyCallback (me: in out) is deferred;
    	---Purpose: The callback function to perform necessary callback action.
        --          Called by the exception handler when it is being destroyed but 
        --          still has this callback registered.

fields

    myHandler:      Address from Standard; -- Pointer to the error handler
    myPrev, myNext: Address from Standard; -- Pointers to the previous and next callback objects
    
friends
    class ErrorHandler
    
end ErrorHandlerCallback;