// bdlma_deleter.h                                                    -*-C++-*-
#ifndef INCLUDED_BDLMA_DELETER
#define INCLUDED_BDLMA_DELETER

#include <bsls_ident.h>
BSLS_IDENT("$Id: $")

//@PURPOSE: Provide a protocol for deleting objects of parameterized type.
//
//@CLASSES:
//   bdlma::Deleter: protocol class for deleting objects
//
//@SEE_ALSO: bslma_allocator
//
//@DESCRIPTION: This component defines the base-level protocol,
// `bdlma::Deleter`, for a thread-safe and type-safe deleter of objects of
// arbitrary type.  This class is extremely useful for transferring the
// ownership of objects between different entities.  The following usage
// example demonstrates this point.
//
///Usage
///-----
// This section illustrates intended use of this component.
//
///Example 1: Basic Usage
/// - - - - - - - - - - -
// Suppose that we would like to transfer ownership of an object between
// threads using `bsl::shared_ptr`.  For the sake of discussion, the type of
// this object is `my_Obj`, we will suppose that it is created using a given
// `basicAllocator`, and that a concrete implementation of `bdlma::Deleter`,
// say `my_Deleter`, is to be used.  Note that we assume that `my_Obj` does not
// require an allocator for any of its members:
// ```
// bslma::NewDeleteAllocator basicAllocator;
// my_Obj *object = new(basicAllocator) my_Obj;
// ```
// Next, create a concrete deleter for `object` using the same allocator as was
// used to allocate its footprint:
// ```
// my_Deleter deleter(&basicAllocator);
// ```
// Finally, create a shared pointer passing to it `object` and the address of
// `deleter`:
// ```
// bsl::shared_ptr<my_Obj> handle(object, &deleter, &basicAllocator);
// ```
// Now the `handle` can be passed to another thread or enqueued efficiently.
// When the reference count of `handle` goes to 0, `object` is automatically
// deleted via the `deleteObject` method of `deleter`, which in turn will
// invoke the destructor of `object`.  Note that since the type of the deleter
// used to instantiate `handle` is `bdlma::Deleter<my_Obj>`, any kind of
// deleter that implements this protocol can be passed.  Also note, on the
// downside, that the lifetime of `deleter` must be longer than the lifetime of
// all associated instances.

#include <bdlscm_version.h>

namespace BloombergLP {
namespace bdlma {

                              // =============
                              // class Deleter
                              // =============

/// Provide a protocol (or pure interface) for a thread-safe object deleter.
template <class TYPE>
class Deleter {

  public:
    // CREATORS

    /// Destroy this object deleter.
    virtual ~Deleter();

    // MANIPULATORS

    /// Destroy the specified `instance` based on its static type and return
    /// its memory footprint to the appropriate memory manager.  Note that a
    /// particular implementation is allowed to destroy this deleter itself.
    virtual void deleteObject(TYPE *instance) = 0;
};

// ============================================================================
//                             INLINE DEFINITIONS
// ============================================================================

// CREATORS
template <class TYPE>
Deleter<TYPE>::~Deleter()
{
}

}  // close package namespace
}  // close enterprise namespace

#endif

// ----------------------------------------------------------------------------
// Copyright 2015 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------
