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The worst part about this is that Apple has decided to once again violate the standard. They purposefully eliminated the `value()` accessor due to ABI issues as

by th0br0 8y ago

The worst part about this is that Apple has decided to once again violate the standard. They purposefully eliminated the `value()` accessor due to ABI issues as far as I understand from the stack overflow comments: https://stackoverflow.com/questions/44217316/how-do-i-use-stdoptional-in-c https://stackoverflow.com/questions/44217316/how-do-i-use-st... My recommendation would be to just use https://github.com/martinmoene/optional-lite https://github.com/martinmoene/optional-lite for cross-platform stuff.

spullara 8y ago
It looks like this is just temporary until the feature is no longer experimental so they can modify the standard library.
klodolph 8y ago
"Violate the standard" might be a bit harsh. The fact that you are using <experimental/optional> instead of <optional> as your header should indicate that something else is going on. Practically speaking, it takes a while for features implemented upstream to make it into your OS of choice. If these are really critical features, you can get third-party implementations of <optional> or you can compile your own toolchain, neither of these are particularly difficult options. It can be a bit frustrating, yes, when language feature arrives on a different schedule in the library and compiler (which happens). Mind you, #include <optional> doesn't work on my Linux box either, with GCC. And if you look at the GCC web page, https://gcc.gnu.org/projects/cxx-status.html#cxx17 https://gcc.gnu.org/projects/cxx-status.html#cxx17, it says that GCC's support for C++17 is "experimental". I know that GCC != Clang, but let's give them some time to test things before a million projects get the code compiled in and we're stuck with the implementation.
- th0br0 8y ago
  GCC moved it to <optional> with the release of GCC7. Note that we're now at GCC8, clang 4 added it - I believe we're now at clang 6. Therefore, it's by far no longer something that's experimental IMHO. (standardised in C++17 after all)

by th0br0 8y ago

spullara 8y ago

It looks like this is just temporary until the feature is no longer experimental so they can modify the standard library.

klodolph 8y ago

"Violate the standard" might be a bit harsh. The fact that you are using <experimental/optional> instead of <optional> as your header should indicate that something else is going on. Practically speaking, it takes a while for features implemented upstream to make it into your OS of choice. If these are really critical features, you can get third-party implementations of <optional> or you can compile your own toolchain, neither of these are particularly difficult options. It can be a bit frustrating, yes, when language feature arrives on a different schedule in the library and compiler (which happens). Mind you, #include <optional> doesn't work on my Linux box either, with GCC. And if you look at the GCC web page, https://gcc.gnu.org/projects/cxx-status.html#cxx17 https://gcc.gnu.org/projects/cxx-status.html#cxx17, it says that GCC's support for C++17 is "experimental". I know that GCC != Clang, but let's give them some time to test things before a million projects get the code compiled in and we're stuck with the implementation.

th0br0 8y ago
GCC moved it to <optional> with the release of GCC7. Note that we're now at GCC8, clang 4 added it - I believe we're now at clang 6. Therefore, it's by far no longer something that's experimental IMHO. (standardised in C++17 after all)