Portable?

[keynan]

I noticed you aren't supporting VC++. Could you elaborate as to the difficulties?

[beark]

It's been a while since I worked on this, so I'm not sure I remember everything. Also, most of what I do remember may no longer be a problem in VS2015 (or whatever the next VS version will be), I haven't really kept track of it.

As for what the problems were, here's a list of things:

• Unrestricted unions. sum_type requires this to work with anything beyond primitive types (which includes maybe and either as they are implemented currently).
• Various TMP-related compiler errors, some/most of which may have been resolved already--I didn't retest for VS2013, since I knew it would still lack other things.
• constexpr, used heavily throughout. Might be possible to fix by only conditionally using them (#ifdef/macros).
• noexcept, similar situations as constexpr.

I think the biggest remaining issue (since VS2013 supports variadic templates) is the unrestricted unions, and perhaps even that could be worked around with std::aligned_union.

However, there's still one pretty big problem: I do not have Windows or VS. So until someone sends a pull request, it's unfortunately not likely to happen.

Summary/TLDR: I don't think there's anything left that couldn't be worked around, but I don't have the tools or means to do so.

[keynan]

VS 2015 preview is out and I think free, being a preview. I'd like to help but I'm not really much a c++ programmer. Even VS 2015 seems to be embarrassingly behind in implementing the c++11 standard, given how much MS claims to use the language.

[zsszatmari]

Hi! I started working on this, however I wouldn't call myself a template guru, so a little hint would be welcome.

template<
typename...Ts,
typename = typename std::enable_if<All<Eq,Ts...>{}>::type
>
bool operator== (const sum_type<Ts...>& a, const sum_type<Ts...>& b) {
size_t i1 = ::ftl::_dtl::sum_type_accessor::activeIndex(a);
size_t i2 = ::ftl::_dtl::sum_type_accessor::activeIndex(b);

    return i1 == i2 && ::ftl::_dtl::sum_type_accessor::compareAt(i1, a, b);
}

Apparently, VS2013 does not like this: typename = typename std::enable_if<All<Eq,Ts...>{}>::type

error C2783: 'bool ftl::operator ==(const ftl::sum_type<Ts...> &,const ftl::sum_type<Ts...> &)' : could not deduce template argument for ''

Any hint on how to achieve the same functionality in a more VS-friendly manner? Or is it even necessary? it might just fail to compile if you try to compare things which are not meant to be compared, but I might be missing a point here, so better ask.

[beark]

One possible cause is that one of the Ts bool operator==(const sum_type&, const sum_type&) is being instantiated for does not have operator== defined. But it seems unlikely, at least if you're just compiling the included tests.

Another guess in blind is that it might help to explicitly refer to the value member of All, as in:

template<
        typename...Ts,
        typename = typename std::enable_if<All<Eq,Ts...>::value>::type
>
bool operator== (const sum_type<Ts...>& a, const sum_type<Ts...>& b) {

Is what you posted the complete output? Are there errors before or after?

Also, if you want better code formatting, syntax highlighting etc in posted code, enclose it in three back-ticks followed by the language code, e.g. like this for C++:

```cpp
some code
 ```

[zsszatmari]

Thanks, ::value did the trick! Sorry for the bad formatting :)

[beark]

No problem, just happy to see someone contributing!