Re: [boost] Formal review for QVM

13 Dec 2015

      I will try to clarify the
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*Conditionally Accepted into Boost*
*  * Conditions for acceptance*
1. The author should provide out of box versions of 2,3,4 dimensions
vector
matrix quaternion classes which can be readily imported by the user and
used (without messing around with traits and such).
There are such class templates: quat<>, vec<> and mat<>. Or do you mean
that you want to have specific typedefs like typedef vec float3
?

I will confess that I had missed that quat<> vec<> and mat<> were already
present. I was hinting at that but the convinient typedefs would definitive
be a plus. Libraries like Eigen and GLM also do it nad it would definitely
enhance the readibility and "out-of-box" usability of the library.   
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*- Did you attempt to use the library? If so:*
  ** Which compiler(s)*
MSVC 2013
  ** What was the experience? Any problems?*
There are certain trivial issues I encountered with MSVC. Emil resolved
them pretty fast in the mailing list but right now, this library is not
very MSVC friendly.
Could you clarify, what do you mean by it is not MSVC-friendly? I've been
using QVM with MSVC for years without a problem except for the MSVC parsing
bug you stumbled upon with (v,A<i>) (I've added that in the known issues
page:

http://zajo.github.io/boost-qvm/known_quirks_and_issues.html).
I thought that bug about the need for default consturctor was a MSVC
thing. I have explained it below and if it is something which I am not
understadning correctly, please point out to me. So essentially I wrote
this small piece of code (same as one before)

#include 
#include <iostream>

class float4
{
public:
float4(float a, float b, float c, float d)
{
container[0] = a;
container[1] = b;
container[2] = c;
container[3] = d;
}
float container[4];
};

namespace boost
{
namespace qvm
{
template<> struct v_traits<float4>
{
static int const dim = 3;
typedef float scalar_type;

template <int I> static inline scalar_type &w(float4 & v) { return
v.container[I]; }
template <int I> static inline scalar_type r(float4 const & v) { return
v.container[I]; }

static inline scalar_type &iw(int i, float4 &v) { return v.container[i]; }
static inline scalar_type ir(int i, float4 const & v) { return
v.container[i]; }
};
}
}

using namespace boost::qvm;

int main()
{
float4 vec(11.0, 0.0, 5.0, -6.0);
1----std::cout << mag(vec);
2----std::cout << mag(normalized(vec));
}

So the issue is that line 1 works without the presence of default
constructor but line 2 needs the same (more specifically the normalized in
place keyword needs it). I weas just wondering if there is a generic way to
enforce this behavior. In the usecases in your tests, most of them use the
default constructor so it doesn't manifest itself too much.  But I read
your comment about returning a qcm::vec<> type and I do understand the
problem you mentioned.
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Re: [boost] Formal review for QVM

Rajaditya Mukherjee