Bug 1803, Upcoming breaking changes for 4.10.0-beta1

Steve Lime Steve.Lime at DNR.STATE.MN.US
Thu Aug 17 16:52:56 EDT 2006

The folks using the various languages would have to chime in on how
the practice in. Seems like Perl is very tolerant, but then again I
wouldn't overwrite
the references like that cause I know the internals. 

Sure seems like a dangerous practice though since once the object goes
out of scope
SWIG reclaims the memory, and then again with the parent object is
freed. Can't see
where allowing that is a good thing.

If folks would like to take a conservative approach and only tackle the
then that's ok with the understanding that it will have to happen


>>> Daniel Morissette <dmorissette at MAPGEARS.COM> 8/17/2006 8:09:45 AM
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
>> the question is how
>> many scripts will the change break and should backward
>> 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
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
end their apps will just be more robust.

The real question that I would throw at the SWIG MapScript experts is:

"Is the practice of overwriting those object references really
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 Morissette

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