Re: [eigen] nesting

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On Fri, Feb 5, 2010 at 8:47 PM, Hauke Heibel
<hauke.heibel@xxxxxxxxxxxxxx> wrote:
> On Fri, Feb 5, 2010 at 10:22 AM, Gael Guennebaud
> <gael.guennebaud@xxxxxxxxx> wrote:
>> So unless someone see how to solve this latter issue, what Hauke is trying
>> to do could work. But instead of specialzing ei_ref_selector for all
>> expressions I would suggest a different approach using new bit Flags. The
>> rules would be as follow:
>> - if the expr has the NestByReference flag, then nest by reference,
>> otherwise nest by value
>> - by default, only Matrix and Array would have the NestByReference flag
>> - the NestByReference flag is not inherited
>> - an expression nesting a temporary would have the NestParentByReference
>> flag
>> - the NestParentByReference flag is not inherited, but if one of the
>> children of an expression has the NestParentByReference flag, then the
>> current expression will have the NestByReference flag. If we make sure that
>> NestParentByReferenceBit == NestByReference>>1, then we simply have to do:
>> Flags = ... | ((Lhs::Flags|Rhs::Flags)&NestParentByReference) << 1), or we
>> could also use a macro: Flags = ... |
>> EIGEN_PROPAGATE_NESTING_BIT(Lhs::Flags|Rhs::Flags).
>
> Just wanted to let you know that in case you decide to do this, I
> volunteer to code it.

great! I'm tempted to say go ahead for it as I cannot see any simpler solution.

> - Hauke
>
>
>



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