[Os-project-managers] The one started this latest round...

[Kipp Martin]

Hi Gus:

So we have to move to 3.0 so AMPL can run mps files?

Cheers


>
>> Let me perhaps try to summarize, in the hopes that this might make it
>> easier for you.
>>
>> First, the problem is that we need an OSInstance object both in
>> OSServiceMethods and in OSSolverService (if we want to print
>> something). We have been making osinstance a data member of
>> oscommandline, which is available everywhere, and is being passed from
>> one routine to the next. Since oscommandline also contains an osil
>> string (along with the name of the OSiL file), this seemed like a
>> clean extension. (OSOptionsStruc did not contain the osinstance, but
>> did contain the osil string.)
>>
>> We populate the osinstance in the oscommandline element in the
>> nonstandard constructor of OSServiceMethods. There we new an
>> OSiLReader, read the osil string into the OSiLReader's m_osinstance
>> element (which is private), and somehow associate it with the
>> oscommandline object.
>>
>> I have been doing a shallow copy (duplicating just the pointer), but
>> that leads to a segfault, because I need to destroy the OSiLReader at
>> the end of the constructor.
>>
>> Alternatives are:
>>
>> 1. allocate the OSiLReader in the OSSolverService and pass it around
>> as an argument of OSServiceMethods
>> 2. make the OSiLReader an element of OSServiceMethods
>> 3. make osilreader->m_osinstance a public member, so that I can
>> NULLify it
>> 4. write a (public) method osilreader->nullifyInstance() that has the
>> same effect
>> 5. do a deep copy of osinstance
>>
>> 5. is my least favorite method. OSInstance objects are large, and
>> copying them is going to take lots of time. I think 1. and 2. are the
>> only real options, but perhaps there is something I have not yet
>> thought of.
>
> As I read this again it occurs to me that this is very similar to the
> problem Walter Weldon raised in ticket 48. I am not sure that I agree a
> deep copy s the answer, but it is a bit frustrating to know that
> elements read in a reader (OSiLReader, OSoLReader, OSrLReader,
> OSCommandLineReader) are only available while the reader is active. I
> have a feeling that this is shortsighted and wrong. I think all my
> problems would be solved if we could make use of smart pointers, such as
> auto_ptr:
>
> http://www.gotw.ca/publications/using_auto_ptr_effectively.htm
>
> Unfortunately it seems that this would change the API and so push us
> into version 3.0.
>
> Cheers
>
> gus
>
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-- 
Kipp Martin
Professor of Operations Research
and Computing Technology
Booth School of Business
University of Chicago
5807 South Woodlawn Avenue
Chicago, IL 60637
773-702-7456
kmartin at chicagobooth.edu
http://www.chicagobooth.edu/faculty/bio.aspx?person_id=12825325568
http://projects.coin-or.org/OS

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