Re: How to get the name of a variable

[Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>]

On Fri, Oct 07, 2011 at 03:18:13PM +0200, Jeroen Demeyer wrote:
> This should be a basic libpari question:
> 
> If I have a variable number (as a long), how can I get the variable name
> (as a string)?  I could of course use GENtostr(pol_x(v)) but there
> should be more direct way.  I looked at the libpari manual, but could
> not find it.

Variable names is GP language concept, while variable number is a libpari concept.
A variable number need not be associated with a variable name.

You can write libpari programs that allocated a variable number but never gives it a name.

Technically, there is a global array varentries[] which returns the entree* associated
to a named variable, or NULL, so you can do:

  entree *ep = varentries[v];
  char *s = ep?(char*)ep->name:NULL;

but probably GENtostr(pol_x(v)) is the best option, especially since we expect to
remove the varentries array.

Cheers,
Bill.