Re: [guppi-list] New Guppi Snapshot

[Jon Trowbridge <trow emccta com>]

On Tue, Aug 29, 2000 at 03:30:47PM +0100, Neil J Pilgrim wrote:
> > > Re multiple views, will multiple views only be possible on multiple
> > > windows (unlinked views)? I'm trying to see a reason for linked views...
> >
> > Yeah, this isn't very flexible.  One problem has been that guppi's
> > "engine" hasn't been good about handling on-the-fly changes to plots,
> > (i.e. adding new elements, etc.) which means things have been pretty
> > static in terms of the layout. 
> 
> Ah. Hard-coded into the 'classes' ? 

Luckily not.  More like just "not implemented yet".

> [tangent]
> I have to confess to wondering why C++ was neglected before: GTK+ uses
> quasi-OO techniques so what difference would it make to people needing
> to learn the code structuring, etc.?
> [/tangent]

If I read your question properly, the answer is "basically none".
Guppi has a (IMHO) nice, clean OO design --- before embarking on Guppi
I'd basically spent 5 or 6 years doing all C++ all the time.

The GTK+ object system gives you pretty much everything you need to do
good OO programs in C.  There are really only three main things missing:

(1) Syntactic Sugar.  All those macro calls can be annoying.
(2) Multiple inheritance.  This hasn't presented a problem in Guppi so
    far.
(3) Templates.  I really like templates, and miss not having them
    around.  But, on the other hand, they also tend to cause a lot of
    problems...

Actually, the GTK+ system better resembles Smalltalk-ish OO than
C++ish OO, since there is a lack of all that strict compile-time checking.


> > > You cannot start a reframe outside of the plot, but can end it
> > > outside.
> > 
> > I original confined the mouse to the window in question during tool
> > ops, but this became annoying for things like dragging.  I figured
> > that there was no harm in this.
> 
> Well no, it enables extension of the range in plots, for example. My
> point was really that you should be able to do the drag in reverse - ie.
> start 'outside' and work inwards. Not that important, just slightly
> asymmetric ;)

It is asymmetric.  But there is one problem: how are you supposed to
know which mouse-clicks outside of the plot range are the start of a
drag?  What if you have two separate scatter plots in the window ---
which one gets it?


> That sounds like a reasonable explanation for what I'm seeing.
> 
> > > In fact, large amounts of:
> > > ---
> > > Gtk-WARNING **: invalid cast from `(unknown)' to `GuppiPlotCanvas'
> > 
> > Yikes... that isn't supposed to happen.  Can you tell me the specific
> > sequence actions that trigger those warnings?
> 
> So far I've not managed to trigger those again, I just noticed them when
> I went back to the xterm I loaded from...I'll let you know if I find
> them again. I think it happened when I hit the home on the graph centre,
> but I'm not sure specifically what I did before that.

If you (or anyone reading this) can figure out how to reproduce that
behavior, please let me know.  All Gtk-WARNINGs must be destroyed.



> Further point: in selection of size data, you cannot now select 'none'
> once something has been chosen other than that?

Fixed.  Thanks.


-JT

-- 
GNU/Linux: Free your mind and your OS will follow.