Re: [Boost-users] [Units] Variant based runtime analysis

28 Feb 2011

      On Feb 28, 10:34 am, alfC  wrote:
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On Feb 28, 2:06 am, Samuel Debionne  wrote:
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I have been playing with things like :
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quantity  >
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That won't work because variant<...>  is not a unit type. Can you post
a small example of what you want to achieve?
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Of course it won't work as is. But I did a bit of hacking in this direction.
the reason I asked for an example is because I was working in
something similar (not the same though).
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My aim is to be able to write something like this :
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any_quantity any_q = myfunction(...);
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quantity<force> = any_q; //runtime check
I think those quantities are so unrelated with each other from a
"type" point of view that you would be better of using templates.
Actually I do this a lot:
template<class Unit>
myfunction(quantity<Unit> q){
...
}
Also I forgot to mention that with the strategy above you have to
deduce the return type of the function, that depends on the logic of
function. typeof_helpers help in this case.

template<class Unit>
quantity< power_typeof_helper< multiply_typeof_helper < ...
Unit ... , ... >::type, ... >::type >
myfunction(quantity<Unit> q){
...

}

I know it can be a drag. I guess auto typed return types in C++0x can
help but I never tried.

Sorry for the splitted answer. In any case I would like to know of any
solution you can come up with.
Alfredo