Initial commit: cframework. Longbow and Libparc

Change-Id: I90378dbd30da6033b20fb1f829b3b822cf366c59
Signed-off-by: Luca Muscariello <lumuscar+fdio@cisco.com>

7 files changed, 998 insertions, 0 deletions

diff --git a/libparc/examples/How To Create A Static PARC Object/main.c b/libparc/examples/How To Create A Static PARC Object/main.c
new file mode 100755
index 00000000..00402170
--- /dev/null
+++ b/libparc/examples/How To Create A Static PARC Object/main.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+#include <stdio.h>
+
+#include <parc/algol/parc_Memory.h>
+#include "parc_MyObject.h"
+
+/*
+ * Three kinds of static PARC Objects
+ *
+ * static or global objects defined within a module
+ *
+ * local objects defined within a function.
+ *
+ */
+
+PARCMyObject *globalObject = parcObject_Instance(PARCMyObject, sizeof(void*), PARCMyObjectSizeOf);
+
+void
+aGlobalObject(void)
+{
+    int x = 1;
+    int y = 2;
+    double z = 3.14;
+
+    parcObject_InitInstance(globalObject, PARCMyObject);
+    parcMyObject_Init(globalObject, x, y, z);
+
+    parcMyObject_Display(globalObject, 0);
+
+    parcMyObject_Release(&globalObject);
+}
+
+static PARCMyObject *staticModuleObject = parcObject_Instance(PARCMyObject, sizeof(void*), PARCMyObjectSizeOf);
+
+void
+aStaticModuleObject(void)
+{
+    int x = 1;
+    int y = 2;
+    double z = 3.14;
+
+    parcObject_InitInstance(staticModuleObject, PARCMyObject);
+    parcMyObject_Init(staticModuleObject, x, y, z);
+
+    parcMyObject_Display(staticModuleObject, 0);
+
+    parcMyObject_Release(&staticModuleObject);
+}
+
+void
+aLocalObject(void)
+{
+    int x = 1;
+    int y = 2;
+    double z = 3.14;
+
+    PARCMyObject *localObject = parcObject_Instance(PARCMyObject, sizeof(void*), PARCMyObjectSizeOf);
+
+    parcObject_InitInstance(localObject, PARCMyObject);
+    parcMyObject_Init(localObject, x, y, z);
+
+    parcMyObject_Display(localObject, 0);
+
+    parcMyObject_Release(&localObject);
+}
+
+void
+aWrappedObject(void)
+{
+    int x = 1;
+    int y = 2;
+    double z = 3.14;
+
+    PARCMyObject *wrappedObject = parcMyObject_Wrap((char[parcObject_TotalSize(sizeof(void*), PARCMyObjectSizeOf)]) { 0 });
+    parcMyObject_Init(wrappedObject, x, y, z);
+
+    parcMyObject_Display(wrappedObject, 0);
+
+    parcMyObject_Release(&wrappedObject);
+}
+
+int
+main(int argc, const char *argv[argc])
+{
+    aGlobalObject();
+
+    aStaticModuleObject();
+
+    aLocalObject();
+
+    aWrappedObject();
+
+    return 0;
+}
diff --git a/libparc/examples/How To Create A Static PARC Object/parc_MyObject.c b/libparc/examples/How To Create A Static PARC Object/parc_MyObject.c
new file mode 100644
index 00000000..9523e494
--- /dev/null
+++ b/libparc/examples/How To Create A Static PARC Object/parc_MyObject.c
@@ -0,0 +1,178 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+/**
+ */
+//#include <config.h>
+
+#include <parc/algol/parc_Object.h>
+#include <parc/algol/parc_DisplayIndented.h>
+#include <parc/algol/parc_Memory.h>
+
+#include "parc_MyObject.h"
+
+// Detect a compile time if a buffer is large enough to hold a structure.
+#define parcObject_DefineXXX(_type_, ...) \
+    typedef struct { __VA_ARGS__ } _ ## _type_; \
+    enum { bytesCompileTimeAssertion = 1 / !!(sizeof(_type_) >= sizeof(_ ## _type_)) }
+
+struct PARCMyObject {
+    int x;
+    double y;
+    double z;
+};
+
+static bool
+_parcMyObject_Destructor(PARCMyObject **instancePtr)
+{
+    assertNotNull(instancePtr, "Parameter must be a non-null pointer to a PARCMyObject pointer.");
+
+
+    /* cleanup the instance fields here */
+    return true;
+}
+
+parcObject_ImplementAcquire(parcMyObject, PARCMyObject);
+
+parcObject_ImplementRelease(parcMyObject, PARCMyObject);
+
+parcObject_Override(
+    PARCMyObject, PARCObject,
+    .destructor = (PARCObjectDestructor *) _parcMyObject_Destructor,
+    .copy = (PARCObjectCopy *) parcMyObject_Copy,
+    .toString = (PARCObjectToString *)  parcMyObject_ToString,
+    .equals = (PARCObjectEquals *)  parcMyObject_Equals,
+    .compare = (PARCObjectCompare *)  parcMyObject_Compare,
+    .hashCode = (PARCObjectHashCode *)  parcMyObject_HashCode,
+    .toJSON = (PARCObjectToJSON *)  parcMyObject_ToJSON);
+
+
+void
+parcMyObject_AssertValid(const PARCMyObject *instance)
+{
+    assertTrue(parcMyObject_IsValid(instance),
+               "PARCMyObject is not valid.");
+}
+
+PARCMyObject *
+parcMyObject_Wrap(void *origin)
+{
+    PARCMyObject *result = parcObject_Wrap(origin, PARCMyObject);
+
+    return result;
+}
+
+PARCMyObject *
+parcMyObject_Init(PARCMyObject *object, int x, double y, double z)
+{
+    if (object != NULL) {
+        object->x = x;
+        object->y = y;
+        object->z = z;
+    }
+
+    return object;
+}
+
+PARCMyObject *
+parcMyObject_Create(int x, double y, double z)
+{
+    PARCMyObject *result = parcObject_CreateInstance(PARCMyObject);
+
+    if (result != NULL) {
+        result->x = x;
+        result->y = y;
+        result->z = z;
+    }
+
+    return (PARCMyObject *) result;
+}
+
+int
+parcMyObject_Compare(const PARCMyObject *instance, const PARCMyObject *other)
+{
+    int result = 0;
+
+    return result;
+}
+
+PARCMyObject *
+parcMyObject_Copy(const PARCMyObject *original)
+{
+    PARCMyObject *result = NULL;
+
+    return result;
+}
+
+void
+parcMyObject_Display(const PARCMyObject *object, int indentation)
+{
+    parcDisplayIndented_PrintLine(indentation, "PARCMyObject@%p { .x=%d .y=%f .z=%f }", object, object->x, object->y, object->z);
+}
+
+bool
+parcMyObject_Equals(const PARCMyObject *x, const PARCMyObject *y)
+{
+    bool result = false;
+
+    if (x == y) {
+        result = true;
+    } else if (x == NULL || y == NULL) {
+        result = false;
+    } else {
+        /* perform instance specific equality tests here. */
+    }
+
+    return result;
+}
+
+PARCHashCode
+parcMyObject_HashCode(const PARCMyObject *instance)
+{
+    PARCHashCode result = 0;
+
+    return result;
+}
+
+bool
+parcMyObject_IsValid(const PARCMyObject *instance)
+{
+    bool result = false;
+
+    if (instance != NULL) {
+        result = true;
+    }
+
+    return result;
+}
+
+PARCJSON *
+parcMyObject_ToJSON(const PARCMyObject *instance)
+{
+    PARCJSON *result = parcJSON_Create();
+
+    if (result != NULL) {
+    }
+
+    return result;
+}
+
+char *
+parcMyObject_ToString(const PARCMyObject *object)
+{
+    char *result = parcMemory_Format("PARCMyObject@%p { .x=%d .y=%f .z=%f }", object, object->x, object->y, object->z);
+
+    return result;
+}
diff --git a/libparc/examples/How To Create A Static PARC Object/parc_MyObject.h b/libparc/examples/How To Create A Static PARC Object/parc_MyObject.h
new file mode 100644
index 00000000..124e734e
--- /dev/null
+++ b/libparc/examples/How To Create A Static PARC Object/parc_MyObject.h
@@ -0,0 +1,368 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+/**
+ * @file parc_MyObject.h
+ * @brief A simple example of how to create static, not allocataed, PARC Objects.
+ *
+ */
+#ifndef PARCLibrary_parc_MyObject
+#define PARCLibrary_parc_MyObject
+#include <stdbool.h>
+
+#include <parc/algol/parc_JSON.h>
+#include <parc/algol/parc_HashCode.h>
+
+parcObject_Declare(PARCMyObject);
+
+/**
+ * The number of bytes sufficient to contain the MyObject data.
+ *
+ * This is dependant upon the definition of the underlying `struct MyObject`.
+ * If that definition changes, it may be necessary to change this constant.
+ */
+#define PARCMyObjectSizeOf 24
+
+/**
+ * Increase the number of references to a `PARCMyObject` instance.
+ *
+ * Note that new `PARCMyObject` is not created,
+ * only that the given `PARCMyObject` reference count is incremented.
+ * Discard the reference by invoking `parcMyObject_Release`.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ *
+ * @return The same value as @p instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     PARCMyObject *b = parcMyObject_Acquire();
+ *
+ *     parcMyObject_Release(&a);
+ *     parcMyObject_Release(&b);
+ * }
+ * @endcode
+ */
+PARCMyObject *parcMyObject_Acquire(const PARCMyObject *instance);
+
+#ifdef PARCLibrary_DISABLE_VALIDATION
+#  define parcMyObject_OptionalAssertValid(_instance_)
+#else
+#  define parcMyObject_OptionalAssertValid(_instance_) parcMyObject_AssertValid(_instance_)
+#endif
+
+/**
+ * Assert that the given `PARCMyObject` instance is valid.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     parcMyObject_AssertValid(a);
+ *
+ *     printf("Instance is valid.\n");
+ *
+ *     parcMyObject_Release(&b);
+ * }
+ * @endcode
+ */
+void parcMyObject_AssertValid(const PARCMyObject *instance);
+
+/**
+ * Create an instance of PARCMyObject
+ *
+ * @return non-NULL A pointer to a valid PARCMyObject instance.
+ * @return NULL An error occurred.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     parcMyObject_Release(&a);
+ * }
+ * @endcode
+ */
+PARCMyObject *parcMyObject_Create(int x, double y, double z);
+
+/**
+ * Set a PARCMyObject instance to it's initial, created state.
+ *
+ * @return non-NULL A pointer to a valid PARCMyObject instance.
+ * @return NULL An error occurred.
+ */
+PARCMyObject *parcMyObject_Init(PARCMyObject *instance, int x, double y, double z);
+
+PARCMyObject *parcMyObject_Wrap(void *origin);
+
+/**
+ * Compares @p instance with @p other for order.
+ *
+ * Returns a negative integer, zero, or a positive integer as @p instance
+ * is less than, equal to, or greater than @p other.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ * @param [in] other A pointer to a valid PARCMyObject instance.
+ *
+ * @return <0 Instance is less than @p other.
+ * @return 0 Instance a and instance b compare the same.
+ * @return >0 Instance a is greater than instance b.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *     PARCMyObject *b = parcMyObject_Create();
+ *
+ *     if (parcMyObject_Compare(a, b) == 0) {
+ *         printf("Instances are equal.\n");
+ *     }
+ *
+ *     parcMyObject_Release(&a);
+ *     parcMyObject_Release(&b);
+ * }
+ * @endcode
+ *
+ * @see parcMyObject_Equals
+ */
+int parcMyObject_Compare(const PARCMyObject *instance, const PARCMyObject *other);
+
+/**
+ * Create an independent copy the given `PARCBuffer`
+ *
+ * A new buffer is created as a complete copy of the original.
+ *
+ * @param [in] original A pointer to a valid PARCMyObject instance.
+ *
+ * @return NULL Memory could not be allocated.
+ * @return non-NULL A pointer to a new `PARCMyObject` instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     PARCMyObject *copy = parcMyObject_Copy(&b);
+ *
+ *     parcMyObject_Release(&b);
+ *     parcMyObject_Release(&copy);
+ * }
+ * @endcode
+ */
+PARCMyObject *parcMyObject_Copy(const PARCMyObject *original);
+
+/**
+ * Print a human readable representation of the given `PARCMyObject`.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ * @param [in] indentation The indentation level to use for printing.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     parcMyObject_Display(a, 0);
+ *
+ *     parcMyObject_Release(&a);
+ * }
+ * @endcode
+ */
+void parcMyObject_Display(const PARCMyObject *instance, int indentation);
+
+/**
+ * Determine if two `PARCMyObject` instances are equal.
+ *
+ * The following equivalence relations on non-null `PARCMyObject` instances are maintained: *
+ *   * It is reflexive: for any non-null reference value x, `parcMyObject_Equals(x, x)` must return true.
+ *
+ *   * It is symmetric: for any non-null reference values x and y, `parcMyObject_Equals(x, y)` must return true if and only if
+ *        `parcMyObject_Equals(y x)` returns true.
+ *
+ *   * It is transitive: for any non-null reference values x, y, and z, if
+ *        `parcMyObject_Equals(x, y)` returns true and
+ *        `parcMyObject_Equals(y, z)` returns true,
+ *        then `parcMyObject_Equals(x, z)` must return true.
+ *
+ *   * It is consistent: for any non-null reference values x and y, multiple invocations of `parcMyObject_Equals(x, y)`
+ *         consistently return true or consistently return false.
+ *
+ *   * For any non-null reference value x, `parcMyObject_Equals(x, NULL)` must return false.
+ *
+ * @param [in] x A pointer to a valid PARCMyObject instance.
+ * @param [in] y A pointer to a valid PARCMyObject instance.
+ *
+ * @return true The instances x and y are equal.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *     PARCMyObject *b = parcMyObject_Create();
+ *
+ *     if (parcMyObject_Equals(a, b)) {
+ *         printf("Instances are equal.\n");
+ *     }
+ *
+ *     parcMyObject_Release(&a);
+ *     parcMyObject_Release(&b);
+ * }
+ * @endcode
+ * @see parcMyObject_HashCode
+ */
+bool parcMyObject_Equals(const PARCMyObject *x, const PARCMyObject *y);
+
+/**
+ * Returns a hash code value for the given instance.
+ *
+ * The general contract of `HashCode` is:
+ *
+ * Whenever it is invoked on the same instance more than once during an execution of an application,
+ * the `HashCode` function must consistently return the same value,
+ * provided no information used in a corresponding comparisons on the instance is modified.
+ *
+ * This value need not remain consistent from one execution of an application to another execution of the same application.
+ * If two instances are equal according to the {@link parcMyObject_Equals} method,
+ * then calling the {@link parcMyObject_HashCode} method on each of the two instances must produce the same integer result.
+ *
+ * It is not required that if two instances are unequal according to the
+ * {@link parcMyObject_Equals} function,
+ * then calling the `parcMyObject_HashCode`
+ * method on each of the two objects must produce distinct integer results.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ *
+ * @return The hashcode for the given instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     PARCHashCode hashValue = parcMyObject_HashCode(buffer);
+ *     parcMyObject_Release(&a);
+ * }
+ * @endcode
+ */
+PARCHashCode parcMyObject_HashCode(const PARCMyObject *instance);
+
+/**
+ * Determine if an instance of `PARCMyObject` is valid.
+ *
+ * Valid means the internal state of the type is consistent with its required current or future behaviour.
+ * This may include the validation of internal instances of types.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ *
+ * @return true The instance is valid.
+ * @return false The instance is not valid.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     if (parcMyObject_IsValid(a)) {
+ *         printf("Instance is valid.\n");
+ *     }
+ *
+ *     parcMyObject_Release(&a);
+ * }
+ * @endcode
+ *
+ */
+bool parcMyObject_IsValid(const PARCMyObject *instance);
+
+/**
+ * Release a previously acquired reference to the given `PARCMyObject` instance,
+ * decrementing the reference count for the instance.
+ *
+ * The pointer to the instance is set to NULL as a side-effect of this function.
+ *
+ * If the invocation causes the last reference to the instance to be released,
+ * the instance is deallocated and the instance's implementation will perform
+ * additional cleanup and release other privately held references.
+ *
+ * @param [in,out] instancePtr A pointer to a pointer to the instance to release.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     parcMyObject_Release(&a);
+ * }
+ * @endcode
+ */
+void parcMyObject_Release(PARCMyObject **instancePtr);
+
+/**
+ * Create a `PARCJSON` instance (representation) of the given object.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ *
+ * @return NULL Memory could not be allocated to contain the `PARCJSON` instance.
+ * @return non-NULL An allocated C string that must be deallocated via parcMemory_Deallocate().
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     PARCJSON *json = parcMyObject_ToJSON(a);
+ *
+ *     printf("JSON representation: %s\n", parcJSON_ToString(json));
+ *     parcJSON_Release(&json);
+ *
+ *     parcMyObject_Release(&a);
+ * }
+ * @endcode
+ */
+PARCJSON *parcMyObject_ToJSON(const PARCMyObject *instance);
+
+/**
+ * Produce a null-terminated string representation of the specified `PARCMyObject`.
+ *
+ * The result must be freed by the caller via {@link parcMemory_Deallocate}.
+ *
+ * @param [in] instance A pointer to a valid PARCMyObject instance.
+ *
+ * @return NULL Cannot allocate memory.
+ * @return non-NULL A pointer to an allocated, null-terminated C string that must be deallocated via {@link parcMemory_Deallocate}.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCMyObject *a = parcMyObject_Create();
+ *
+ *     char *string = parcMyObject_ToString(a);
+ *
+ *     parcMyObject_Release(&a);
+ *
+ *     parcMemory_Deallocate(&string);
+ * }
+ * @endcode
+ *
+ * @see parcMyObject_Display
+ */
+char *parcMyObject_ToString(const PARCMyObject *instance);
+
+#endif
diff --git a/libparc/examples/How To Create an Object Pool/main.c b/libparc/examples/How To Create an Object Pool/main.c
new file mode 100644
index 00000000..710d3d7c
--- /dev/null
+++ b/libparc/examples/How To Create an Object Pool/main.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "parc_SimpleBufferPool.h"
+
+int
+main(int argc, char *argv[argc])
+{
+    PARCSimpleBufferPool *pool = parcSimpleBufferPool_Create(3, 10);
+
+    PARCBuffer *buffer = parcSimpleBufferPool_GetInstance(pool);
+    parcBuffer_Release(&buffer);
+
+    buffer = parcSimpleBufferPool_GetInstance(pool);
+    parcBuffer_Release(&buffer);
+
+    parcSimpleBufferPool_Release(&pool);
+
+    return 0;
+}
diff --git a/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.c b/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.c
new file mode 100644
index 00000000..fbd71b6e
--- /dev/null
+++ b/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.c
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+#include <stdio.h>
+
+#include <parc/algol/parc_Object.h>
+#include <parc/algol/parc_DisplayIndented.h>
+#include <parc/algol/parc_Memory.h>
+
+#include <parc/algol/parc_LinkedList.h>
+
+#include "parc_SimpleBufferPool.h"
+
+struct PARCSimpleBufferPool {
+    size_t bufferSize;
+    size_t limit;
+    PARCLinkedList *freeList;
+    PARCObjectDescriptor *descriptor;
+};
+
+static bool
+_parcSimpleBufferPool_Destructor(PARCSimpleBufferPool **instancePtr)
+{
+    assertNotNull(instancePtr, "Parameter must be a non-null pointer to a PARCSimpleBufferPool pointer.");
+
+    PARCSimpleBufferPool *pool = *instancePtr;
+
+    parcLinkedList_Apply(pool->freeList, (void (*))parcObject_SetDescriptor, (const void *) &PARCBuffer_Descriptor);
+
+    parcLinkedList_Release(&pool->freeList);
+
+    return true;
+}
+
+static bool
+_parcSimpleBufferPool_BufferDestructor(PARCBuffer **bufferPtr)
+{
+    PARCBuffer *buffer = *bufferPtr;
+    *bufferPtr = 0;
+
+    PARCSimpleBufferPool *bufferPool = parcObjectDescriptor_GetTypeState(parcObject_GetDescriptor(buffer));
+
+    if (bufferPool->limit > parcLinkedList_Size(bufferPool->freeList)) {
+        parcLinkedList_Append(bufferPool->freeList, buffer);
+    } else {
+        parcBuffer_Acquire(buffer);
+        parcObject_SetDescriptor(buffer, &parcObject_DescriptorName(PARCBuffer));
+        parcBuffer_Release(&buffer);
+    }
+
+    return false;
+}
+
+parcObject_ImplementAcquire(parcSimpleBufferPool, PARCSimpleBufferPool);
+
+parcObject_ImplementRelease(parcSimpleBufferPool, PARCSimpleBufferPool);
+
+parcObject_Override(PARCSimpleBufferPool, PARCObject,
+                    .destructor = (PARCObjectDestructor *) _parcSimpleBufferPool_Destructor);
+
+PARCSimpleBufferPool *
+parcSimpleBufferPool_Create(size_t limit, size_t bufferSize)
+{
+    PARCSimpleBufferPool *result = parcObject_CreateInstance(PARCSimpleBufferPool);
+
+    if (result != NULL) {
+        result->limit = limit;
+        result->bufferSize = bufferSize;
+        result->freeList = parcLinkedList_Create();
+
+        char *string;
+        asprintf(&string, "PARCSimpleBufferPool=%zu", bufferSize);
+        result->descriptor = parcObjectDescriptor_CreateExtension(&parcObject_DescriptorName(PARCBuffer), string);
+        free(string);
+        result->descriptor->destructor = (PARCObjectDestructor *) _parcSimpleBufferPool_BufferDestructor;
+        result->descriptor->typeState = (PARCObjectTypeState *) result;
+    }
+
+    return result;
+}
+
+PARCBuffer *
+parcSimpleBufferPool_GetInstance(PARCSimpleBufferPool *bufferPool)
+{
+    PARCBuffer *result;
+
+    if (parcLinkedList_Size(bufferPool->freeList) > 0) {
+        result = parcLinkedList_RemoveFirst(bufferPool->freeList);
+    } else {
+        result = parcBuffer_Allocate(bufferPool->bufferSize);
+        parcObject_SetDescriptor(result, bufferPool->descriptor);
+    }
+
+    return result;
+}
diff --git a/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.h b/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.h
new file mode 100644
index 00000000..fe8ddf4a
--- /dev/null
+++ b/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.h
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+/**
+ * @file parc_BufferPool.h
+ * @brief <#Brief Description#>
+ *
+ * <#Detailed Description#>
+ *
+ */
+#ifndef PARCLibrary_parc_BufferPool
+#define PARCLibrary_parc_BufferPool
+#include <stdbool.h>
+
+#include <parc/algol/parc_Object.h>
+
+parcObject_Declare(PARCSimpleBufferPool);
+
+/**
+ * Increase the number of references to a `PARCBufferPool` instance.
+ *
+ * Note that new `PARCBufferPool` is not created,
+ * only that the given `PARCBufferPool` reference count is incremented.
+ * Discard the reference by invoking `parcSimpleBufferPool_Release`.
+ *
+ * @param [in] instance A pointer to a valid PARCBufferPool instance.
+ *
+ * @return The same value as @p instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCBufferPool *a = parcSimpleBufferPool_Create();
+ *
+ *     PARCBufferPool *b = parcSimpleBufferPool_Acquire();
+ *
+ *     parcSimpleBufferPool_Release(&a);
+ *     parcSimpleBufferPool_Release(&b);
+ * }
+ * @endcode
+ */
+PARCSimpleBufferPool *parcSimpleBufferPool_Acquire(const PARCSimpleBufferPool *instance);
+
+/**
+ * Create an instance of PARCBufferPool
+ *
+ * <#Paragraphs Of Explanation#>
+ *
+ * @return non-NULL A pointer to a valid PARCBufferPool instance.
+ * @return NULL An error occurred.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCBufferPool *a = parcSimpleBufferPool_Create();
+ *
+ *     parcSimpleBufferPool_Release(&a);
+ * }
+ * @endcode
+ */
+PARCSimpleBufferPool *parcSimpleBufferPool_Create(size_t highWater, size_t bufferSize);
+
+/**
+ * Release a previously acquired reference to the given `PARCBufferPool` instance,
+ * decrementing the reference count for the instance.
+ *
+ * The pointer to the instance is set to NULL as a side-effect of this function.
+ *
+ * If the invocation causes the last reference to the instance to be released,
+ * the instance is deallocated and the instance's implementation will perform
+ * additional cleanup and release other privately held references.
+ *
+ * @param [in,out] instancePtr A pointer to a pointer to the instance to release.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSimpleBufferPool *a = parcSimpleBufferPool_Create();
+ *
+ *     parcSimpleBufferPool_Release(&a);
+ * }
+ * @endcode
+ */
+void parcSimpleBufferPool_Release(PARCSimpleBufferPool **instancePtr);
+
+PARCBuffer *parcSimpleBufferPool_GetInstance(PARCSimpleBufferPool *bufferPool);
+
+#endif
diff --git a/libparc/examples/How To Extend a PARCObject/HowToExtendAPARCObject.c b/libparc/examples/How To Extend a PARCObject/HowToExtendAPARCObject.c
new file mode 100644
index 00000000..e98018d7
--- /dev/null
+++ b/libparc/examples/How To Extend a PARCObject/HowToExtendAPARCObject.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+/**
+ *
+ * This example shows a simple extention of an existing PARC Object implementation
+ * (PARCString) to replace the default implementation of the Compare() function with another.
+ *
+ * The demonstration shows how to reverse the sort order of a PARCSortedList
+ * containing a list of PARCString instances without changing PARCSortedList nor PARCString.
+ *
+ */
+#include <stdio.h>
+
+#include <parc/algol/parc_SortedList.h>
+#include <parc/algol/parc_String.h>
+
+/*
+ * This is the default behaviour of the PARCSortedList implementation.
+ */
+void
+forwardOrder(void)
+{
+    PARCSortedList *sortedList = parcSortedList_Create();
+
+    PARCString *aaa = parcString_Create("aaa");
+    PARCString *aab = parcString_Create("aab");
+    PARCString *aac = parcString_Create("aac");
+
+    parcSortedList_Add(sortedList, aaa);
+    parcSortedList_Add(sortedList, aab);
+    parcSortedList_Add(sortedList, aac);
+
+    parcSortedList_Display(sortedList, 0);
+    parcString_Release(&aaa);
+    parcString_Release(&aab);
+    parcString_Release(&aac);
+}
+
+/*
+ * This function will be substituted for the default Compare implementation in the PARCString object.
+ */
+int
+parcString_ReverseCompare(const PARCString *string, const PARCString *other)
+{
+    return parcString_Compare(string, other) * -1;
+}
+
+parcObject_Extends(PARCReverseString, PARCString,
+                   .compare = (PARCObjectCompare *) parcString_ReverseCompare);
+
+
+PARCString *
+parcMyString_Create(const char *string)
+{
+    PARCString *result = parcString_Create(string);
+
+    // By setting the descriptor to our special descriptor here, we effectively
+    // substitute the default compare function with our parcString_ReverseCompare
+    parcObject_SetDescriptor(result, &parcObject_DescriptorName(PARCReverseString));
+
+    return result;
+}
+
+void
+reverseOrder(void)
+{
+    PARCSortedList *sortedList = parcSortedList_Create();
+
+    PARCString *aaa = parcMyString_Create("aaa");
+    PARCString *aab = parcMyString_Create("aab");
+    PARCString *aac = parcMyString_Create("aac");
+
+    parcSortedList_Add(sortedList, aaa);
+    parcSortedList_Add(sortedList, aab);
+    parcSortedList_Add(sortedList, aac);
+
+    parcSortedList_Display(sortedList, 0);
+    parcString_Release(&aaa);
+    parcString_Release(&aab);
+    parcString_Release(&aac);
+}
+
+int
+main(int argc, const char *argv[argc])
+{
+    forwardOrder();
+    reverseOrder();
+    return 0;
+}