Re: [Celestia-developers] adding a gettrackedobject method to celx

[vincent <vin...@fr...>]

Chris,

Actually, making gettrackobject/getselection return nil could
break some former scripts. Indeed, some script writers may have
applied the name() call 'celestia:getselection:name()' to an
empty selection since this was the only way to know whether this
selection was empty or not. If the selection was indeed empty,
'celestia:getselection:name() then returned "?".
The problem is that these scripts wouldn't work anymore since
name() can't be applied to a nil value...

@+
Vincent


Selon vincent <vin...@fr...>:

> Chris,
>
> I hope you had a great trip to Alaska ! :-)
> I've checked in my change to CVS. Here are some further change
> that makes gettrackedobject/getselection return nil when no
> object is tracked/selected :
>
>
> Index: src/celestia/celx.cpp
> ===================================================================
> RCS file: /cvsroot/celestia/celestia/src/celestia/celx.cpp,v
> retrieving revision 1.105
> diff -u -r1.105 celx.cpp
> --- src/celestia/celx.cpp	16 Apr 2007 10:27:32 -0000	1.105
> +++ src/celestia/celx.cpp	16 Apr 2007 17:23:36 -0000
> @@ -3265,7 +3265,11 @@
>      checkArgs(l, 1, 1, "No arguments expected to
> observer:gettrackedobject");
>
>      Observer* o = this_observer(l);
> -    object_new(l, o->getTrackedObject());
> +    Selection obj = o->getTrackedObject();
> +    if (obj.getType() == Selection::Type_Nil)
> +        lua_pushnil(l);
> +    else
> +        object_new(l, obj);
>
>      return 1;
>  }
> @@ -4216,7 +4220,10 @@
>      checkArgs(l, 1, 1, "No arguments expected to
> celestia:getselection()");
>      CelestiaCore* appCore = this_celestia(l);
>      Selection sel = appCore->getSimulation()->getSelection();
> -    object_new(l, sel);
> +    if (sel.getType() == Selection::Type_Nil)
> +        lua_pushnil(l);
> +    else
> +        object_new(l, sel);
>
>      return 1;
>  }
>
>
> Please let me know if this is OK to you.
>
> @+
> Vincent
>
>
> Selon Chris Laurel <cl...@gm...>:
>
> > Vincent,
> >
> > Sorry for the long delay. I just returned from my trip to Alaska
> .
> > . .  Your change looks good. I think we should consider changing
> > gettrackedobject and getselection to return nil when there's no
> > object tracked or selected. But, this discussion can occur
> > independent of your change.
> >
> > --Chris
> >
> > On 4/12/07, vincent <vin...@fr...> wrote:
> > >
> > > Selon vincent <vin...@fr...>:
> > >
> > > > The 'gettrackedobject()' function return "?" when no object
> > > > is currently tracked, precisely as the 'getselection()'
> > > > function does when no object is currently selected.
> > >
> > > Well, actually, getttrackedobject():name() returns "?" when no
> > > object is currently tracked. As for that, I noticed that
> > > 'gettrackedobject', as well as 'getselection', don't return
> > > 'nil' when no object is tracked or selected. So one can't write
> > > something like :
> > >
> > >     sel = celestia:getselection()
> > >     if sel == nil then
> > >         ...
> > >
> > > The only way to know whether the selection is empty or not
> > > is to apply the name() field on it:
> > >
> > >     sel = celestia:getselection()
> > >     if sel:name() == "?" then
> > >         ...
> > >
> > > Could someone confirm that ?
> > >
> > > Chris, can I check in my changes ?
> > >
> > > @+
> > > Vincent
>
>
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@+
Vincent