Re: [ 1496624 ] bug manifested in internal function commands

[Ethan A M. <merritt@u.washington.edu>]

On Monday 29 May 2006 04:06 am, Hans-Bernhard Br=F6ker wrote:
>=20
> The problem is in 'reset': that command is not supposed to as much as=20
> *look* at the user-defined variables in the first place, much less=20
> remove any of them, whether they're in limbo or not.

It only removes undefined variables. This is only garbage-collection
mechanism we have for such space, so if you remove it we will end
up with the opposite problem of a memory leak.

The issue is that the parsing code uses add_udv(), which results in=20
space allocation for every variable mentioned, whether or not it is
a correctly defined variable. For example:
	print nonsense
allocates space for a variable "nonsense" before reporting that it
is undefined.  This space will only be released if you later define
"nonsense" properly, or do a reset.=20

> gnuplot> f(x) =3D x+a
> gnuplot> g(x) =3D x+b
> gnuplot> plot f(x)
>         undefined variable: a
I am inclined to say that the definition of f(x) should fail if there=20
is no previously-defined variable 'a'.

Alternatively, the code that creates an evaluation stack for 'f(x)'
could initialize a to 0 rather than leaving it undefined.


=2D-=20
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742