-- Created on: 2006-04-13
-- Created by: Andrey BETENEV
-- Copyright (c) 2006-2012 OPEN CASCADE SAS
--
-- The content of this file is subject to the Open CASCADE Technology Public
-- License Version 6.5 (the "License"). You may not use the content of this file
-- except in compliance with the License. Please obtain a copy of the License
-- at http://www.opencascade.org and read it completely before using this file.
--
-- The Initial Developer of the Original Code is Open CASCADE S.A.S., having its
-- main offices at: 1, place des Freres Montgolfier, 78280 Guyancourt, France.
--
-- The Original Code and all software distributed under the License is
-- distributed on an "AS IS" basis, without warranty of any kind, and the
-- Initial Developer hereby disclaims all such warranties, including without
-- limitation, any warranties of merchantability, fitness for a particular
-- purpose or non-infringement. Please see the License for the specific terms
-- and conditions governing the rights and limitations under the License.


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;