Re: [Boost-users] [proto] Question on grammar and operator overloading

Subject: Re: [Boost-users] [proto] Question on grammar and operator overloading
From: Hal Finkel (half_at_[hidden])
Date: 2009-10-06 11:33:47

Joel,

Do you mean proto-izing std::complex itself (or some derived class), or
using (extending) proto::terminal < std::complex >?

On a related note, is there a standard way (yet) of changing a single
component of std::complex? I'm not sure that there is...

A recent working group draft has:
T real() const;
void real(T);
T imag() const;
void imag(T);

The Apache stdcxx has only:
T real() const;
T imag() const;

And the GNU libstdc++ has:
_Tp& real(); 
const _Tp& real() const;
_Tp& imag();
const _Tp& imag() const;

My rationale for using an array value type was to make the
interpretation of the type as a 2-element array clean. I'm working with
several scientific codes which contain complex types defined as:
typedef double complex_t[2]; and I'm preparing to port them to use more
modern C++. However, I think that your point about the use of intrinsic
functions is a good one.

 -Hal

On Tue, 2009-10-06 at 15:15 +0200, joel wrote:
> > Either way. You could even just use some other terminal type besides 
> boost::array. std::complex or std::pair would do.
> 
> Just dropping in as I have the exact same code lying around. Using 
> std::complex itself as the underlying type of complex terminal is 
> actually a good idea. When you'll have to do thing like cos( z ), you 
> may want to go cak to call std::cos on complex as on some platform it 
> uses some intrinsic that are faster than rewriting the cosinus by 
> yourself. Moreover std::complex isn't more than a pair of T anyway.
>