Bug 1803, Upcoming breaking changes for 4.10.0-beta1

[Umberto Nicoletti]

Hi all,
got back today and I have already a bug report because of the changes
approved in this thread: an API change in 4.10 and probably another in
5 is not too respectful of our users I guess.

Now since the majority of the devs has voted in favour of the proposal
and I do not have veto rights I'll go on and downgrade the Java
examples to the newer functionality, but needless to say I'm *very
disappointed* and I'll consider proposing to make some of these
changes c-sharp specific since the fatal errors that Tamas seems to
experience in c-sharp I cannot reproduce them in Java.

Umberto

On 8/18/06, Tamas Szekeres <szekerest at gmail.com> wrote:
> Along with Frank's +1 on the IRC we have at least +3 so i have
> committed the changes.
> HISTORY.TXT contains the interface elements affected.
>
> /me thinks it was a bit sweaty but was worth the trouble
>
> Tamas
>
>
> 2006/8/17, Steve Lime <Steve.Lime at dnr.state.mn.us>:
> > +1 from me too. The nice thing it's a beta release so there's still time
> > if we
> > find we've overstepped a boundary. This is good discussion and I want
> > to
> > thank Tamas for the investigative work and solution (and Umberto for
> > taking
> > time from vacation - you're more generous than I!)...
> >
> > Steve
> >
> > >>> Daniel Morissette <dmorissette at MAPGEARS.COM> 8/17/2006 4:03:53 PM
> > >>>
> > After a bit more thinking and discussion on IRC, I am with Steve and
> > also think that all the members that are listed in Steve's email can
> > safely be made immutable since it would not make sense to attempt to
> > overwrite them anyway. (That's also the way things are in PHP MapScript
> >
> > and that never stopped us from doing anything).
> >
> > With respect to imageObj.format, I think it should be made read-only or
> >
> > hidden since we get an imageObj from methods that create the actual
> > image, and changing the outputFormatObj on the image after it's been
> > created is just asking for trouble (not to mention the possible object
> >
> > referencing issues that Tamas is trying to address).
> >
> > I give my +1 to go ahead with this.
> >
> > Also please make sure you include a note listing the members that were
> >
> > made immutable in HISTORY.TXT.
> >
> > Daniel
> >
> > Steve Lime wrote:
> > > Umberto: How do you add classes and layers at runtime? In the context
> > of
> > > a layer or a map
> > > correct? I don't believe that what Tamas is proposing would change
> > that
> > > capability at all.
> > >
> > > If you look at the list:
> > >
> > > classObj.layer
> > > webObj.map
> > > legendObj.map
> > > layerObj.map
> > >
> > > are back references and you don't want folks monkeying around with
> > > them.
> > >
> > > classObj.label
> > > legendObj.label
> > > mapObj.scalebar
> > > mapObj.legend
> > > mapObj.querymap
> > > mapObj.web
> > > mapObj.symbolset
> > > mapObj.labelcache
> > > mapObj.reference
> > >
> > > Already exist in their parent objects so there is no need to create
> > new
> > > ones in place of the
> > > existing ones. Users should get the reference to the existing
> > structure
> > > and modify it in place.
> > > I'm not sure that given the potential problems that it even makes
> > sense
> > > to have constructors
> > > for these. I assume this is the contentious spot...
> > >
> > > (If there is a glaring need to have, for example, an unattached
> > > labelObj laying around then
> > > couldn't a populateFrom capability be developed for a labelObj, or
> > > perhaps setLabel() for a
> > > classObj?)
> > >
> > > classObj.metadata
> > > fontSetObj.fonts
> > > mapObj.configoptions
> > > webObj.metadata
> > >
> > > Are hash tables and Sean created a nice interface for them to use.
> > > Modifying directly shouldn't
> > > be allowed. I think this is what was ok'd yesterday.
> > >
> > > Note sure about  imageObj.format...
> > >
> > > I guess I don't see the big deal with this change. My 2 cents.
> > >
> > > Steve
> > >
> > >
> > >>>>Umberto Nicoletti <umberto.nicoletti at GMAIL.COM> 8/17/2006 8:25 AM
> > >>>>
> > >
> > > On 8/17/06, Daniel Morissette <dmorissette at mapgears.com> wrote:
> > >
> > >>Tamas Szekeres wrote:
> > >>
> > >>>>I think you can safely hide the labelPathObj, that should not be
> > >>>>exposed. I think the others
> > >>>>should be immutable too (assuming I understand the problem
> > >
> > > correctly),
> > >
> > >>>>the question is how
> > >>>>many scripts will the change break and should backward
> > >
> > > compatability
> > >
> > >>>>breakage be limited
> > >>>>to major releases (e.g. 5.0).
> > >>>>
> > >>>
> > >>>Those scripts are *erroneous* !  It would be desirable to force
> > >
> > > the
> > >
> > >>>users to put them into a good shape as soon as possible.
> > >>>
> > >>>
> > >>
> > >>It seems that I should take position as release manager but
> > >>unfortunately I do not know or use SWIG MapScript much so I have to
> > >
> > > rely
> > >
> > >>on those who know to make an opinion on whether the current stuff is
> > >>dangerous enough to warrant breaking a few scripts with 4.10.
> > >>
> > >>Based on the understanding I have of the problem from reading this
> > >>thread and previous discussions, it seems to me that if those
> > >
> > > scripts
> > >
> > >>are doing something that is just waiting to bomb then changing SWIG
> > >>MapScript in v4.10 to make those object references immutable is not
> > >
> > > a
> > >
> > >>backwards compatibility issue, it is a bugfix and a service we are
> > >>making to those users by forcing them to fix their scripts... and in
> > >
> > > the
> > >
> > >>end their apps will just be more robust.
> > >>
> > >
> > >
> > > Daniel,
> > > IMO  we are talking about fixing pieces of code we are not even sure
> > > they are broken. For instance I have some Java mapscript tests (and
> > an
> > > application) running just fine that add layers and classes at run
> > time
> > > and that's why I am so reluctant in approving this proposal. Only
> > once
> > > we get a test case that reproduces this errors reliably then we can
> > go
> > > and change the code.
> > >
> > > Unfortunately I couldn't join the IRC meeting because I am on
> > vacation
> > > otherwise I'd have spoken  earlier (I am writing this on the road).
> > >
> > > Regards,
> > > Umberto
> > >
> > >
> > >>The real question that I would throw at the SWIG MapScript experts
> > >
> > > is:
> > >
> > >>"Is the practice of overwriting those object references really
> > >
> > > dangerous
> > >
> > >>or not?"
> > >>
> > >>If the answer is yes then I think that solves the question and we
> > >
> > > need
> > >
> > >>to apply the fix and force users to fix their scripts.
> > >>
> > >>If there are object references that can safely be overwritten (such
> > >
> > > as
> > >
> > >>colorObj) then my opinion is that we should not touch them in 4.10.
> > >>
> > >>Daniel
> > >>--
> > >>Daniel Morissette
> > >>http://www.mapgears.com/
> > >>
> > >
> > >
> >
> >
> > --
> > Daniel Morissette
> > http://www.mapgears.com/
> >
>