Index: src/OFArray.h
==================================================================
--- src/OFArray.h
+++ src/OFArray.h
@@ -13,11 +13,11 @@
 #import "OFDataArray.h"
 
 /**
  * The OFArray class provides a class for storing objects in an array.
  */
-@interface OFArray: OFObject
+@interface OFArray: OFObject <OFCopying>
 {
 	OFDataArray *array;
 }
 
 /**
@@ -33,17 +33,10 @@
 /**
  * \return The objects of the array as a C array
  */
 - (id*)data;
 
-/**
- * Clones the OFArray, creating a new one.
- *
- * \return A new autoreleased copy of the OFArray
- */
-- (id)copy;
-
 /**
  * Returns a specific object of the OFDataArray.
  *
  * \param index The number of the object to return
  * \return The specified object of the OFArray

Index: src/OFDataArray.h
==================================================================
--- src/OFDataArray.h
+++ src/OFDataArray.h
@@ -16,11 +16,11 @@
  * array.
  *
  * If you plan to store large hunks of data, you should consider using
  * OFBigDataArray, which allocates the memory in pages rather than in bytes.
  */
-@interface OFDataArray: OFObject
+@interface OFDataArray: OFObject <OFCopying>
 {
 	char   *data;
 	size_t itemsize;
 	size_t count;
 }
@@ -64,17 +64,10 @@
 /**
  * \return All elements of the OFDataArray
  */
 - (void*)data;
 
-/**
- * Clones the OFDataArray, creating a new one.
- *
- * \return A new autoreleased copy of the OFDataArray
- */
-- (id)copy;
-
 /**
  * Compares the OFDataArray to another object.
  *
  * \param obj An object to compare with
  * \return An integer which is the result of the comparison, see for example
@@ -117,10 +110,10 @@
  * \param nitems The number of items to remove
  */
 - removeNItems: (size_t)nitems;
 @end
 
-@interface OFBigDataArray: OFDataArray
+@interface OFBigDataArray: OFDataArray <OFCopying>
 {
 	size_t size;
 }
 @end

Index: src/OFObject.h
==================================================================
--- src/OFObject.h
+++ src/OFObject.h
@@ -116,10 +116,11 @@
  */
 - (BOOL)isEqual: (id)obj;
 
 /**
  * Calculate a hash for the object.
+ *
  * Classes containing data (like strings, arrays, lists etc.) should reimplement
  * this!
  *
  * \return A 32 bit hash for the object
  */
@@ -209,5 +210,15 @@
  * Deallocates the object and also frees all memory allocated via its memory
  * pool.
  */
 - (void)dealloc;
 @end
+
+/**
+ * Objects implementing this protocol can be copied.
+ */
+@protocol OFCopying
+/**
+ * \return A copy of the object
+ */
+- (id)copy;
+@end

Index: src/OFString.h
==================================================================
--- src/OFString.h
+++ src/OFString.h
@@ -16,11 +16,11 @@
 #import "OFArray.h"
 
 /**
  * A class for managing strings.
  */
-@interface OFString: OFObject
+@interface OFString: OFObject <OFCopying>
 {
 	char	     *string;
 #ifdef __objc_INCLUDE_GNU
 	unsigned int length;
 #else
@@ -79,17 +79,10 @@
 /**
  * \return The length of the OFString
  */
 - (size_t)length;
 
-/**
- * Clones the OFString, creating a new one.
- *
- * \return A new autoreleased copy of the OFString as a OFMutableString
- */
-- (id)copy;
-
 /**
  * Compares the OFString to another object.
  *
  * \param obj An object to compare with
  * \return An integer which is the result of the comparison, see for example