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manfred.doudar_at_[hidden]

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Manfred
MetOcean Engineers
Jeff Garland wrote:
>On Mon, 15 Nov 2004 10:35:35 +0800, Manfred Doudar wrote
>  
>
>>c/-  All:
>>
>>In taking a holistic look at some of the work I do, I've come
>>to realize a need for a "transparent" data type, and wondering
>>whether or not it exists.
>>
>>As all of you would have experienced, any organization has such
>>a representation of such a type; be it called:
>>
>>  "Null value", "Missing value", "Fill value", "Infinity" ,
>>
>>or whatever.
>>
>>What I am hoping for is support for such an representation,
>>with existing containers and algorithms; such that if you
>>perform any mathematical operation, (arithmetic, transcendental;
>>inverse; anything really ...); that you get back the *same*
>>object (ie. it passes transparently through any operation), and
>>not raise any exception if you so choose.
>>
>>   Example:
>>
>>         missing_val == atan(missing_val) - missing_val;
>>         missing_val == 1 / missing_val;
>>         missing_val == missing_val + missing_val;
>>         missing_val == missing_val - missing_val;
>>
>>         typedef std::vector<any_type> dVec;
>>         dVec some_vector;
>>
>>            ... populate some_vector ...
>>
>>         dVec::iterator = some_vector.find(missing_val);
>>
>>Boosters, do we have such a representation; is there value in having
>>such a thing in Boost; is there a (simple) alternative work-around ??
>>    
>>
>
>In date-time there is a template called int_adapter in the implementation that
>lets you have nan, infinities, etc in an integer value type.  I think this is
>something like what you are trying to do.  Basically it steals some values
>from the integer type and treats them as special then overrides the operators
>accordingly.  We use this to implement operations on date-time special values
>like not-a-date-time.
>
>See boost/date_time/int_adapter and libs/date_time/test/testint_adapter.cpp
>for details.  
>
>HTH,
>
>Jeff
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