Ilya Zakharevich on Wed, 10 May 2000 16:58:52 -0400

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Re: Extensible type system

On Fri, May 05, 2000 at 12:53:40AM +0200, Bill Allombert wrote:
> Yes, but we have to add support for rings first, and then add ideals.

I got an idea that it may be not that hard to add extensible-type
infrastructure to PARI.  (Think of accessing Macaulay data from PARI.)

Add a new type with the first word as before, the second being a
pointer to a "dispatch table" (C struct with function pointers), and
the other words type-specific.  Populate the dispatch table by
functions which call err("blah unimplemented").

What can be a minimal contents of the dispatch table?  "Convert to
GEN", "clone", "gerepile" (what will it do?), "print", "printtex",
"delete"?  I think this is enough for pilot implementation...

Starting from this, one could add more entries into the table to
optimize some operations (say, avoid convertion to PARI for some