--- a/ExternalStructure.st	Mon Jan 28 14:43:30 2013 +0100
+++ b/ExternalStructure.st	Mon Jan 28 19:01:20 2013 +0100
@@ -9,7 +9,6 @@
  other person.  No title to or ownership of the software is
  hereby transferred.
 "
-
 "{ Package: 'stx:libbasic' }"
 
 ExternalBytes subclass:#ExternalStructure
@@ -65,12 +64,56 @@
 
 fromExternalAddress:anExternalAddress
     ^ self new fromExternalAddress:anExternalAddress
+!
+
+new
+    "allocate some memory usable for data;
+     the memory is not controlled by the garbage collector.
+     Return a corresponding ExternalBytes object or raise MallocFailure (if malloc fails).
+
+     Use this, if you have to pass a block of bytes to some
+     external destination (such as a C function) which does not copy the
+     data, but instead keeps a reference to it. For example, many functions
+     which expect strings simply keep a ref to the passed string - for those,
+     an ST/X string-pointer is not the right thing to pass, since ST/X objects
+     may change their address.
+
+     DANGER ALERT: the memory is NOT automatically freed until it is either
+                   MANUALLY freed (see #free) or the returned externalBytes object
+                   is unprotected or the classes releaseAllMemory method is called."
+
+    ^ super new:(self sizeof)
+
+    "Modified: / 20-12-2010 / 16:22:51 / cg"
+!
+
+unprotectedNew
+    "allocate some memory usable for data;
+     the memory is under the control of the garbage collector.
+     Return a corresponding ExternalBytes object or raise MallocFailure (if malloc fails).
+
+     DANGER ALERT: the memory block as allocated will be automatically freed
+                   as soon as the reference to the returned externalBytes object
+                   is gone (by the next garbage collect).
+                   If the memory has been passed to a C-function which
+                   remembers this pointer, bad things may happen ...."
+
+    ^ super unprotectedNew:(self sizeof)
 ! !
 
 !ExternalStructure class methodsFor:'queries'!
 
 cType
     ^ cType
+!
+
+sizeof
+    "the sizeof my instances in bytes"
+
+    cType notNil ifTrue:[
+        ^ cType sizeof
+    ].
+    self subclassResponsibility
 ! !
 
 !ExternalStructure methodsFor:'private'!
@@ -82,5 +125,6 @@
 !ExternalStructure class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/ExternalStructure.st,v 1.3 2006-06-20 15:27:17 ca Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/ExternalStructure.st,v 1.4 2013-01-28 18:01:20 cg Exp $'
 ! !
+