Re: [Boost-users] [Boost][mpl] vector_c boolean operations

"Noel Belcourt" writes:

On Oct 1, 2005, at 6:57 PM, David Abrahams wrote:

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"Noel Belcourt" writes:

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So if I want to perform an element-wise mpl::or operation of two sequences (r, p1) and then test the resulting sequence for equivalence to the input sequence, something like this should work since as you observe below, mpl::equal will compare two sequences and yield a scalar boolean.

BOOST_MPL_ASSERT((equal >::type>));

One more observation about this, this code doesn't compile if r and p1 are a vector_c or a vector_c with CW 9.5 on Tiger 10.4.2. The compiler output is attached.

For example, if r and p1 are declared as follows, the code will not compile.

typedef vector_c r,p1; BOOST_MPL_ASSERT(( equal >::type>));

The problem seems to be that the sequence produced by invoking transform using a boolean binary function is a different type than vector_c.

I think that's not really the issue. I think the problem is that the _element_ types of those two sequuences are not identical.

The fix is trivial.

typedef vector_c r,p1; BOOST_MPL_ASSERT(( equal >::type, transform >::type>));

While clunky, this works, and also works if we declare r and p1 as vector_c.

Actually I think that's technically nonportable. I'm guessing the right thing to do is use find, one way or the other. This is typedef transform > >::type x; BOOST_MPL_ASSERT(( is_same< find_if::type , end_<x>::type > ));

Just want to be sure that this is known and expected behavior?

I'm actually unsure. Aleksey?

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BOOST_MPL_ASSERT(( equal_to<

I think this should be is_same. Sorry for the mistake.

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find< zip_view , not_equal_to,or_,second<_> >

...

::type , end >::type

))

I'll be sure to read up on zip_view and try this out.

Thanks for your help.

-- Noel

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