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diff --git a/include/apr_optional.h b/include/apr_optional.h
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+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+#ifndef APR_OPTIONAL_H
+#define APR_OPTIONAL_H
+
+#include "apu.h"
+/** 
+ * @file apr_optional.h
+ * @brief APR-UTIL registration of functions exported by modules
+ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** 
+ * @defgroup APR_Util_Opt Optional Functions
+ * @ingroup APR_Util
+ *
+ * Typesafe registration and retrieval of functions that may not be present
+ * (i.e. functions exported by optional modules)
+ * @{
+ */
+
+/**
+ * The type of an optional function.
+ * @param name The name of the function
+ */
+#define APR_OPTIONAL_FN_TYPE(name) apr_OFN_##name##_t
+
+/**
+ * Declare an optional function.
+ * @param ret The return type of the function
+ * @param name The name of the function
+ * @param args The function arguments (including brackets)
+ */
+#define APR_DECLARE_OPTIONAL_FN(ret,name,args) \
+typedef ret (APR_OPTIONAL_FN_TYPE(name)) args
+
+/**
+ * XXX: This doesn't belong here, then!
+ * Private function! DO NOT USE! 
+ * @internal
+ */
+
+typedef void (apr_opt_fn_t)(void);
+/** @internal */
+APU_DECLARE_NONSTD(void) apr_dynamic_fn_register(const char *szName, 
+                                                  apr_opt_fn_t *pfn);
+
+/**
+ * Register an optional function. This can be later retrieved, type-safely, by
+ * name. Like all global functions, the name must be unique. Note that,
+ * confusingly but correctly, the function itself can be static!
+ * @param name The name of the function
+ */
+#define APR_REGISTER_OPTIONAL_FN(name) do { \
+  APR_OPTIONAL_FN_TYPE(name) *apu__opt = name; \
+  apr_dynamic_fn_register(#name,(apr_opt_fn_t *)apu__opt); \
+} while (0)
+
+/** @internal
+ * Private function! DO NOT USE! 
+ */
+APU_DECLARE(apr_opt_fn_t *) apr_dynamic_fn_retrieve(const char *szName);
+
+/**
+ * Retrieve an optional function. Returns NULL if the function is not present.
+ * @param name The name of the function
+ */
+#define APR_RETRIEVE_OPTIONAL_FN(name) \
+	(APR_OPTIONAL_FN_TYPE(name) *)apr_dynamic_fn_retrieve(#name)
+
+/** @} */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* APR_OPTIONAL_H */