Re: [boost] Seeking endorsement for the reflection library (PFR)

Subject: Re: [boost] Seeking endorsement for the reflection library (PFR)
From: Peter Dimov (lists_at_[hidden])
Date: 2017-11-06 12:22:40

Antony Polukhin wrote:
> Yes, but the macro idea came to me first. MPL is slow and adds dependency 
> to Boost library, so I'm avoiding it right now.

I was thinking about mp11, not MPL. :-)

> > Flat/precise strikes me as odd though. Do we have to have both? Precise 
> > seems to be what I'd always want.
>
> Flat reflection is left there mostly for users that wish to use library on 
> a C++14 compiler and do not wish to exploit the core language defect. But 
> you are right, most of the users will prefer precise reflection.

>From your talk I was left with the impression that everything needed for 
precision already worked on C++14? The only problem is that you have to 
reinterpret_cast to a layout-compatible type instead of using structured 
bindings.

Initially I though that flat is what you get because you can initialize 
aggregates with the total "flat" element count due to brace elision:

struct X1
{
    int a, b;
};

struct X2
{
    double c, d;
};

struct X3
{
    X1 x1;
    X2 x2;
};

auto x3 = X3{ 1, 2, 3, 4 };

but then I tried it with ubiq{} and it doesn't work. So this is not a 
problem and the fields can be counted "precisely". So what's the issue?