[libcxx-commits] [PATCH] D102121: [libcxx][ranges] adds _`non-propagating-cache`_

[Mark de Wever via Phabricator via libcxx-commits]

Mordante added inline comments.


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Comment at: libcxx/include/__ranges/non_propagating_cache.h:42
+  // may refer to internal details of the source view.
+  template<class _Tp>
+  class __non_propagating_cache {
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Quuxplusone wrote:
> Mordante wrote:
> > http://eel.is/c++draft/range.nonprop.cache#1.1 `non-propagating-cache<T> constrains its type parameter T with is_­object_­v<T>.`
> This is undetectable, and therefore it's cheaper (in terms of compile time and source code simplicity) not to bother with it.
Ok. (It just makes me wonder why it's specified in the Standard.)


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Comment at: libcxx/include/__ranges/non_propagating_cache.h:87
+    constexpr void __set(_Tp&& __value) { __value_.emplace(_VSTD::move(__value)); }
+  };
+
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Quuxplusone wrote:
> Mordante wrote:
> > I miss http://eel.is/c++draft/range.nonprop.cache#1.6
> > ```
> > non-propagating-cache<T> has an additional member function template specified as follows:
> > 
> > template<class I>
> >   constexpr T& emplace-deref(const I& i);    // exposition only
> > 
> > ```
> > Is that intentionally?
> Exposition-only members are undetectable, and anyway it looks like //`emplace-deref`// is equivalent to `this->emplace(*i)`.
> See tcanens' comment https://reviews.llvm.org/D102121#inline-965635
Then it seems it's indeed intentionally.


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D102121/new/

https://reviews.llvm.org/D102121