Re: gp_read_str

[Dirk Laurie <dirk.laurie@gmail.com>]

2012/6/14 Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>:

> Maybe it would help if you explained what you really want to do with them?

I'm trying to embed Pari in a Lua framework.  The typical user program starts

   x=gen"x"

The Lua x is now a pointer to the same object as the Pari x.  By providing Lua
bindings for addition etc, I can build up quite a complicated object from that
one x.  But it doesn't have a Pari name attached to it, being made from return
values of Pari functions.  The references are only associated with names in
the Lua state.

Now I want to assign that object to something that gp_read_str can see.  The
reason being that the interface is fairly small and I can't anticipate which
of the 750-plus functions known to GP might be needed.  So I want to write a
Lua-callable C function that will take a pointer still referenced to in the Lua
state and put it somewhere in the namespace know to gp_read_str.  Then anything
that GP could do, Lua could also do.

There is such a namespace, since if I say e.g. gen"p=1+x+x^2" there is now
an object called "p" known to gp_read_str.  As the libpari manual states.

But if gp_read_str can store something that it computed in a place called
"p", surely there must be some other routine in the Pari library that can
store an existing GEN there too?