Re: Reading objects from a file

[paulg@loxinfo.co.th (Paul Sjoerdsma)]

paulg@loxinfo.co.th (Paul Sjoerdsma) wrote:

  >Hi,
  >
  >I'm just starting using Ada and I have a, hopefully simple, question.
  >
  >First I'll explain what I am trying to do:
  >
  >I am rewriting a simple visualization program, which is used to output
  >geological (actually micro-paleontological) data. The program needs to
  >read frequence curves, process the data and output files.
  >The data structures used will

I posted the previous message while it wasn't finished. Here is the
rest.

The data structures used (for the graphics part) will look something
like:

Graphic_Elem (base class)
-- Line_Elem (child class)
-- Polyline_Elem (child class)
-- Solid_Elem (child class)
etc

The output would go tho=20
Graphic_Port (base class)
Dxf_port (child class)
Ascii_port (child class)

There will also be a class Figure
procedure Add(Figure, Graphic_Elem)
procedure Draw(Figure, Graphic_Port)


What I am looking for are methods for the Figure class
procedure Read
procedure Write

in such a way that invoking Read(Figure) will build the appropriate
structure. So when it encounters a saved Line_Elem in the file it will
invoke the read procedure associated with the Line_Elem.

regards
Paul