Re: [Plplot-devel] plenv() issues

[Maurice L. <mj...@ga...>]

Joao Cardoso writes:
 > On Wednesday 06 November 2002 06:17, Maurice LeBrun wrote:
 > > Alan W. Irwin writes:
 > >  > On Tue, 5 Nov 2002, [iso-8859-1] Jo=E3o Cardoso wrote:
 > >  > > What do you think of this problem? Is there a "cure" that doe=
s not
 > >  > > influence other users?
 > >  >
 > >  > How about define plenv0 which does everything but the page adva=
nce?=20
 > >  > Then define plenv as the combination of pladv and plenv0.
 > >  >
 > >  > I know this adds one more piece of public API that we have to p=
ropagate
 > >  > to all the language interfaces *and* document, but that is pret=
ty
 > >  > straightforward, and we currently have so many variations on ou=
r startup
 > >  > commands (think of all the plstart variations), and our advance=
 page
 > >  > commands, that adding another convenient plenv variation isn't =
that big
 > >  > a deal IMO.
 > >  >
 > >  > Geoffrey and Maurice, is such a solution OK with you?
 > >
 > > Sure.  I've never been completely happy with the behavior of plenv=
 in this
 > > regard either.
 >=20
 > OK, I will work on it soon.
 >=20
 > Do you think that plenv0() should clear the page? I think it should!=


Seems reasonable.  There may be some cases where the user doesn't want =
it
cleared but these are probably rare and not worth API support. =20

Sigh.. I must admit to some dislike of the proliferation of API calls. =
 I
would greatly prefer we handle these kinds of cases through some sort o=
f
option-setting procedure.  E.g. instead of calling plenv0(...), one wou=
ld
do:

plsopt("plenv_advance", "0");
plenv(...)

Then you never need to expand the API (complete with the myriad of lang=
uage
bindings needed), just add a new option.

I've actually implemented such a scheme for my own libraries, twice now=
, once
in Fortran and more recently in iTcl.  Because there are times when you=
 want
the option to be set forever, I'd use plsdopt(...) to set an option
permanently (default); plsopt would only take effect until the next new=
 plot.
That way you could avoid non-local effects.  It works great.

Anyway, I've got no time for any of this right now, so for now we're st=
uck
with the usual addition to the API.

 > As plclear() is not currently working (no driver but the gnome one s=
upports=20
 > it) I will also change it, issuing a solid fill with the background =
color=20
 > when the driver does not support clear.=20

Looks good.

--=20
Maurice LeBrun    mj...@ga...
Research Organization for Information Science and Technology of Japan (=
RIST)