Re: OO Style with Ada Containers

[braver <deliverable@gmail.com>]

OK, here's how I ended up switching most of my sample application to
object-prefix notation.  It gets a Vector of tokens and inserts them
into an Ordered_Map to count word occurrences:

	loop
		Get_Line(Line, Line_Last);
		exit when End_Of_File;
		declare
			use Ngrams.Token_Vectors;
			Tokens : Ngrams.Token_Vector := Ngrams.Split_Vector (Line,
Line_Last);

			Token_Cursor : Cursor := Tokens.First;
			s : SU.Unbounded_String;
			Count : Natural;
		begin
			while Has_Element(Token_Cursor) loop
				s := Element(Token_Cursor);
				-- NB is there a Natural'Inc?
				Total_Word_Count := Total_Word_Count + 1;

				declare
					use Word_Counts;
				begin
					Ngram_Cursor := Ngram_Counts.Find(s);

					-- would need to import "=" for private type WC.Cursor:
					-- if Ngram_Cursor = WC.No_Element
					if not Has_Element(Ngram_Cursor) then
						Ngram_Counts.Insert(s, 1);
						New_Word_Count := New_Word_Count + 1;
					else -- a valid position in Ngram_Pos
						Count := Element(Ngram_Cursor);
						Ngram_Counts.Replace_Element(Ngram_Cursor, Count+1);
						-- or -- but it also replaces the key:
						-- WC.Replace(Ngram_Counts, s, Count+1);
					end if;
				end;

				Next(Token_Cursor);
			end loop;
		end;
	end loop;

	declare
		use Word_Counts;
	begin
		Ngram_Cursor := Ngram_Counts.First;
		while Has_Element(Ngram_Cursor) loop
			Put_Line(SU.To_String(Key(Ngram_Cursor)) &
				Positive'Image(Element(Ngram_Cursor)));
			Next(Ngram_Cursor);
		end loop;
	end;

As you can see, I've managed to do prefix notation everywhere except
cursors.  How do they coexist with prefix notation -- or are they
replaced by something cooler already, too?  :)

I'd appreciate any improvements to the above, which I deduced from ARM
and Rosetta Stone examples in an hour and then prefix'ised thanks to
Adam's hint!  (Well I've followed Ada since 1987 so the spirit is easy
to follow...)

Cheers,
Alexy