There really isn't a way in Ada to represent the record the way you're asking for. However, since your concern really isn't with how the record is represented in memory, but rather with how it's transmitted to a socket, you probably don't need to worry about record representation clauses.
Instead, you can define your own Write
routine:
procedure Write (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in My_Record_T);
for My_Record_T'Write use Write;
or, I believe this will work in Ada 2012:
type My_Record_T is record
...
end record
with Write => Write;
procedure Write (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in My_Record_T);
and then the body will look like
procedure Write (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in My_Record_T) is
begin
-- Write out the record components, EXCEPT Array_Length and The_Array.
T1'Write (Stream, Item.F1); -- F1 is a record field, T1 is its type
T2'Write (Stream, Item.F2); -- F2 is a record field, T2 is its type
...
-- Now write the desired data
declare
Data_To_Write : Array_Type_T (1 .. Item.Array_Length)
renames Item.The_Array (1 .. Item.Array_Length);
-- I'm assuming the lower bound is 1, but if not, adjust your code
-- accordingly
begin
Array_Type_T'Write (Stream, Data_To_Write);
-- Note: using 'Write will write just the data, without any bound
-- information, which is what you want.
end;
end Write;
This won't work if the other components need to be packed, though, e.g. if you want to write a byte to the socket that contains one 3-bit record component and one 5-bit record component. If that's necessary, I don't think the built-in 'Write
attributes will do that for you; you may need to do your own bit-twiddling, or you could get tricky and define an array of Stream_Elements
and use an Address
clause or aspect to define an array that overlays the rest of the record. But I wouldn't use the overlay method unless I were 100% certain that the reader at the other end of the socket were an Ada program that uses the exact same type definition.
Note: I haven't tested this.