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From: Eric Niebler (eric_at_[hidden])
Date: 2008-07-02 18:34:29

Joel de Guzman wrote:
> Eric Niebler wrote:
>> BOOST_TYPEOF can't perfectly distinguish between lvalues and
>> rvalues.
> Yeah, that's my basic problem with BOOST_TYPEOF.
>> I fudge it where I have to,
> Where do you fudge it? if_then expression? How? How about ordinary
> operators like a + b? Do you simply not allow weird uses like:
> X& operator+(A a, B b)
> return a reference??

I use BOOST_TYPEOF to get the type of an expression. Then, I check to
see if the expression can bind to a non-const reference using the sizeof
trick. If it does, then I treat the result as an lvalue and add a
reference to the expression's type. It gets the answer wrong for
const-qualified rvalues, but in the above example, it would correctly
deduce the type of "A()+B()" to be "X&".

Eric Niebler
BoostPro Computing

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