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#ifndef __com_sun_star_uno_XInterface_idl__
#define __com_sun_star_uno_XInterface_idl__


 module com {  module sun {  module star {  module uno {

/** base interface of all UNO interfaces

    <p> It provides lifetime control by reference counting and the
    possibility of querying for other
    interfaces of the same logical object.


    <p>
    "Logical Object" in this case means that the
    interfaces actually can be supported by internal (e.g. aggregated) physical objects.</p>

    <p> Deriving from this interface is mandatory for all UNO interfaces.
    <p> Each language binding (Java, C++, StarBasic, Python, ... ) may
    provide a different mapping of this interface, please look into the language
    dependent documentation.

    <p> The UNO object does not export the state of the reference count (acquire() and
        release() do not have return values). In general, also the UNO object itself
        should not make any assumption on the concrete value of the reference count
        (except on the transition from one to zero ).

 */
published interface XInterface
{
    /** queries for a new interface to an existing UNO object.
        <p>
        The queryInterface() method is the entry point to obtain other interfaces which
        are exported by the object. The caller asks the implementation of the object,
        if it supports the interface specified by the type argument. The call may either
        return with a interface reference of the requested type or with a void any.

        <p>
        There are certain specifications, a queryInterface() implementation must not violate.
        <p>
        1) If queryInterface on a specific object has once returned a valid interface reference
          for a given type, it must return a valid reference for any successive queryInterface
          calls on this object for the same type.
        <p>
        2) If queryInterface on a specific object has once returned a null reference
        for a given type, it must always return a null reference for the same type.
        <p>
        3) If queryInterface on a reference A returns reference B, queryInterface on
        B for Type A must return interface reference A or calls made on the returned
        reference must be equivalent to calls made on reference A.
        <p>
        4) If queryInterface on a reference A returns reference B, queryInterface on
        A and B for XInterface must return the same interface reference (object identity).

        <p> The reason for the strong specification is, that a Uno Runtime Environment (URE)
        may choose to cache queryInterface() calls.
        <p> As mentioned above, certain language bindings may map this function differently also
        with different specifications, please visit the language dependent specification for it.
        The current C++ binding sticks to the specification state
        <p>
        The rules mentioned above are basically identical to the rules of QueryInterface in MS COM.

        @param aType a UNO interface type, for which an object reference shall be obtained.
        @return an interface reference in case the requested interface is supported by the object,
                a void any otherwise.
     */
    any queryInterface( [in] type aType );

    /** increases the reference counter by one.

        <p>When you have called acquire() on the
        UNO object, it is often said, that you have a reference or a hard reference
        to the object.

        <p>
        It is only allowed to invoke a method on a UNO object, when you keep
        a hard reference to it.

        <p> Every call to acquire must be followed by a corresponding call to release
        some time later, which may eventually lead to the destruction of the object.
     */
    void acquire();

    /** decreases the reference counter by one.
        <p>When the reference counter reaches 0, the object gets deleted.</p>
        <p>Calling release() on the object is often called releasing
        or clearing the reference to an object.
     */
    void release();

};


}; }; }; };

#endif

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