pragma todo added

doc/pragma-skiss.txt

+Discussion 141023
+
+TODO:
+
+*** new labcomm packet types:
+    TYPE_DEF = 0x03     // for (possibly) hierarchical type definitions
+    TYPE_BINDING = 0x04 // binding a sample def to a type def
+
+*** rewrite malloc of received samples to utilize the packet length field
+    to allocate a single object before parsing the sample byte stream
+
+*** labcomm language: add type for type_ref to facilitate references to
+    labcomm sample_defs (and type_defs) in (primarily) pragmas
+    E.g.,  sample ... foo;
+         sample ... bar;
+
+         sample struct {
+             ...
+             type[2] some_refs;
+         } some_pragma;
+
+	my_lc_some_pragma sp;
+
+	sp.some_refs = {&labcomm_signature_my_lc_foo, 
+                        &labcomm_signature_my_lc_bar}; 
+         
+ 	labcomm_encode_my_lc_some_pragma(enc, &sp);
+
+    This is to avoid exposing local_to_remote and remote_to_local
+
+*** refactor {encoder,decoder}registry to separate the actual encoder
+    from the registry
+
+    - currently, the assignment of local indices is done in the "constructor"
+      which means that the registries will be very thin
+
+*** labcomm_pragma_builder(struct labcomm_encoder *enc);
+
+    - looks like an encoder to enable reuse of the generated encode functions
+    - allocates memory in the enclosing encoder, enc.
+    - deallocates memory when packet is sent
+
+*** Pragma handler
+    - is a decoder, to which the user registers handlers for pragma samples
+    - has/gets a byte_array_reader in the context
+    - the "surrounding" decoder will deallocate the pragma packet when the
+      pragma handler returns
+
+
+
+
+______________________________________________________________
+______________preliminary sketch of pragma____________________
+
+
 A pragma "packet" is a sequence of fields, where each field is
 a labcomm sample (in order to keep labcomm in-band self-describing).
 
@@ -56,6 +111,8 @@ alt 1. standard handlers, parameter pragma_type to handle function
 	-- this means adding a parameter to all handlers
            (where null means not pragma)
 
+void handle_some_pragma(some_pragma *v, void *context, char * pragma_type);
+
 alt 2. standard handlers, but separate register_pragma_handler function
        use the handler context to store and communicate pragma-specific data.
 
@@ -63,9 +120,21 @@ alt 2. standard handlers, but separate register_pragma_handler function
            and that the handler context for pragmas need to be specified
            (by labcomm)
 
-1.
+alt 3  have a single handler for pragma packets as the interface upwards
+       from the labcomm lib. That handler is then responsible for managing
+       and multiplexing pragma types based on the type field in the pragma
+       packet.
 
-void handle_some_pragma(some_pragma *v, void *context, char * pragma_type);
+       The labcomm libraries can provide a default implementation of a
+       pragma_handler, to facilitate the common cases and reduce the
+       amount of boilerplate code.
+
+struct pragma_packet {
+	char *pragma_type;
+	char *packed_data;
+}
+
+void handle_pragma(struct pragma_packet *p, void *context);