Index: src/OFArray.h
==================================================================
--- src/OFArray.h
+++ src/OFArray.h
@@ -137,10 +137,16 @@
 - (OFString*)componentsJoinedByString: (OFString*)separator;
 
 - addObject: (OFObject*)obj;
 - addObject: (OFObject*)obj
     atIndex: (size_t)index;
+- replaceObject: (OFObject*)old
+     withObject: (OFObject*)new;
+- replaceObjectAtIndex: (size_t)index
+	    withObject: (OFObject*)obj;
+- replaceObjectIdenticalTo: (OFObject*)old
+		withObject: (OFObject*)new;
 - removeObject: (OFObject*)obj;
 - removeObjectIdenticalTo: (OFObject*)obj;
 - removeObjectAtIndex: (size_t)index;
 - removeNObjects: (size_t)nobjects;
 - removeNObjects: (size_t)nobjects

Index: src/OFArray.m
==================================================================
--- src/OFArray.m
+++ src/OFArray.m
@@ -308,10 +308,31 @@
 					      selector: _cmd];
 }
 
 - addObject: (OFObject*)obj
     atIndex: (size_t)index
+{
+	@throw [OFNotImplementedException newWithClass: isa
+					      selector: _cmd];
+}
+
+- replaceObject: (OFObject*)old
+     withObject: (OFObject*)new
+{
+	@throw [OFNotImplementedException newWithClass: isa
+					      selector: _cmd];
+}
+
+- replaceObjectAtIndex: (size_t)index
+	    withObject: (OFObject*)obj
+{
+	@throw [OFNotImplementedException newWithClass: isa
+					      selector: _cmd];
+}
+
+- replaceObjectIdenticalTo: (OFObject*)old
+		withObject: (OFObject*)new
 {
 	@throw [OFNotImplementedException newWithClass: isa
 					      selector: _cmd];
 }
 

Index: src/OFMutableArray.h
==================================================================
--- src/OFMutableArray.h
+++ src/OFMutableArray.h
@@ -31,18 +31,47 @@
  */
 - addObject: (OFObject*)obj
     atIndex: (size_t)index;
 
 /**
- * Removes the first object equivalent to the specified object.
+ * Replaces all objects equivalent to the first specified object with the
+ * second specified object.
+ *
+ * \param old The object to replace
+ * \param new The replacement object
+ */
+- replaceObject: (OFObject*)old
+     withObject: (OFObject*)new;
+
+/**
+ * Replaces the object at the specified index with the specified object.
+ *
+ * \param index The index of the object to replace
+ * \param obj The replacement object
+ */
+- replaceObjectAtIndex: (size_t)index
+	    withObject: (OFObject*)obj;
+
+/**
+ * Replaces all objects that have the same address as the first specified object
+ * with the second specified object.
+ *
+ * \param old The object to replace
+ * \param new The replacement object
+ */
+- replaceObjectIdenticalTo: (OFObject*)old
+		withObject: (OFObject*)new;
+
+/**
+ * Removes all objects equivalent to the specified object.
  *
  * \param obj The object to remove
  */
 - removeObject: (OFObject*)obj;
 
 /**
- * Removes the first object that has the same address as the specified object.
+ * Removes all objects that have the same address as the specified object.
  *
  * \param obj The object to remove
  */
 - removeObjectIdenticalTo: (OFObject*)obj;
 

Index: src/OFMutableArray.m
==================================================================
--- src/OFMutableArray.m
+++ src/OFMutableArray.m
@@ -48,10 +48,59 @@
 	       atIndex: index];
 	[obj retain];
 
 	return self;
 }
+
+- replaceObject: (OFObject*)old
+     withObject: (OFObject*)new
+{
+	OFObject **objs = [array cArray];
+	size_t i, count = [array count];
+
+	for (i = 0; i < count; i++) {
+		if ([objs[i] isEqual: old]) {
+			[new retain];
+			[objs[i] release];
+			objs[i] = new;
+		}
+	}
+
+	return self;
+}
+
+- replaceObjectAtIndex: (size_t)index
+	    withObject: (OFObject*)obj
+{
+	OFObject **objs = [array cArray];
+
+	if (index >= [array count])
+		@throw [OFOutOfRangeException newWithClass: isa];
+
+	[obj retain];
+	[objs[index] release];
+	objs[index] = obj;
+
+	return self;
+}
+
+- replaceObjectIdenticalTo: (OFObject*)old
+		withObject: (OFObject*)new
+{
+	OFObject **objs = [array cArray];
+	size_t i, count = [array count];
+
+	for (i = 0; i < count; i++) {
+		if (objs[i] == old) {
+			[new retain];
+			[objs[i] release];
+			objs[i] = new;
+		}
+	}
+
+	return self;
+}
 
 - removeObject: (OFObject*)obj
 {
 	OFObject **objs = [array cArray];
 	size_t i, count = [array count];
@@ -58,11 +107,10 @@
 
 	for (i = 0; i < count; i++) {
 		if ([objs[i] isEqual: obj]) {
 			[objs[i] release];
 			[array removeItemAtIndex: i];
-			return self;
 		}
 	}
 
 	return self;
 }

Index: tests/OFArray.m
==================================================================
--- tests/OFArray.m
+++ tests/OFArray.m
@@ -64,10 +64,31 @@
 	TEST(@"-[indexOfObject:]", [a[0] indexOfObject: c_ary[1]] == 1)
 
 	TEST(@"-[indexOfObjectIdenticalTo:]",
 	    [a[0] indexOfObjectIdenticalTo: c_ary[1]] == 1)
 
+	TEST(@"-[replaceObject:withObject:]",
+	    [a[0] replaceObject: c_ary[1]
+		     withObject: c_ary[0]] &&
+	    [[a[0] objectAtIndex: 0] isEqual: c_ary[0]] &&
+	    [[a[0] objectAtIndex: 1] isEqual: c_ary[0]] &&
+	    [[a[0] objectAtIndex: 2] isEqual: c_ary[2]])
+
+	TEST(@"-[replaceObject:identicalTo:]",
+	    [a[0] replaceObjectIdenticalTo: c_ary[0]
+				withObject: c_ary[1]] &&
+	    [[a[0] objectAtIndex: 0] isEqual: c_ary[1]] &&
+	    [[a[0] objectAtIndex: 1] isEqual: c_ary[1]] &&
+	    [[a[0] objectAtIndex: 2] isEqual: c_ary[2]])
+
+	TEST(@"-[replaceObjectAtIndex:withObject:]",
+	    [a[0] replaceObjectAtIndex: 0
+			    withObject: c_ary[0]] &&
+	    [[a[0] objectAtIndex: 0] isEqual: c_ary[0]] &&
+	    [[a[0] objectAtIndex: 1] isEqual: c_ary[1]] &&
+	    [[a[0] objectAtIndex: 2] isEqual: c_ary[2]])
+
 	TEST(@"-[removeObject:]",
 	    [a[0] removeObject: c_ary[1]] && [a[0] count] == 2)
 
 	TEST(@"-[removeObjectIdenticalTo:]",
 	    [a[0] removeObjectIdenticalTo: c_ary[2]] && [a[0] count] == 1)