source: mainline/uspace/dist/src/sysel/demos/iface.sy

--
-- Copyright (c) 2010 Jiri Svoboda
-- All rights reserved.
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions
-- are met:
--
-- o Redistributions of source code must retain the above copyright
--   notice, this list of conditions and the following disclaimer.
-- o Redistributions in binary form must reproduce the above copyright
--   notice, this list of conditions and the following disclaimer in the
--   documentation and/or other materials provided with the distribution.
-- o The name of the author may not be used to endorse or promote products
--   derived from this software without specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
-- IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
-- OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
-- IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
-- INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
-- NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
-- THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--

class InterfaceDemo is
        fun Main(), static is
                -- Create new instance of Foo
                var f : Foo;
                f = new Foo();

                -- Variable of interface type
                var g : IA/int;

                -- Implicit conversion to interface implemented by Foo
                g = f;

                -- Explicit conversion of interface type IA/int to class type
                -- Foo. Foo is implementing the interface IA/int.
                f = g as Foo;

                Console.WriteLine(g.a());
        end
end

-- Generic interface implemented by class Foo
interface IA/t is
        fun a() : t;
end

-- Non-generic interface implemented by class Foo
interface IB is
        fun b();
        prop P : int is
                get;
                set value;
        end
end

-- Base class of Foo
class A is
end

-- Class unrelated to Foo
class B is
end

-- Foo is derived from A and implements IA/int and IB
class Foo : A + IA/int + IB is
        fun a() : int is
                return 0;
        end

        fun b() is
        end

        prop P : int is
                get is
                        return 1;
                end
                set value is
                end
        end
end