C++17 feature proposal: Allow type trait variable templates

Daniel Cheng

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Jan 6, 2022, 3:41:36 PM1/6/22

to cxx

It saves typing, e.g. instead of:

std::is_pointer<T>::value

One can simply write:

std::is_pointer_v<T>

With only 80 columns, each character is precious :)

Example:

https://chromium-review.googlesource.com/c/chromium/src/+/3370735

Daniel

dan...@chromium.org

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Jan 6, 2022, 3:53:31 PM1/6/22

to Daniel Cheng, cxx

Yes I would like to see us use these now.

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Avi Drissman

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Jan 6, 2022, 3:54:07 PM1/6/22

to Daniel Cheng, cxx

+1

On Thu, Jan 6, 2022 at 3:41 PM Daniel Cheng <dch...@chromium.org> wrote:

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Peter Kasting

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Jan 6, 2022, 3:59:23 PM1/6/22

to Daniel Cheng, cxx

+1

PK

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Jeremy Roman

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Jan 6, 2022, 4:20:07 PM1/6/22

to Peter Kasting, Daniel Cheng, cxx

+1, though FWIW std::is_pointer<T>() has always been as short. :)

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Will Cassella

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Jan 6, 2022, 5:17:24 PM1/6/22

to cxx, Jeremy Roman, Daniel Cheng, cxx, Peter Kasting

+1, code involving <type_traits> can often be somewhat difficult to read, this feature improves readability.

Roland Bock

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Jan 7, 2022, 2:41:39 AM1/7/22

to Will Cassella, cxx, Jeremy Roman, Daniel Cheng, Peter Kasting

+1

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Honglin Yu

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Jan 7, 2022, 5:39:05 AM1/7/22

to Roland Bock, Will Cassella, cxx, Jeremy Roman, Daniel Cheng, Peter Kasting

+1, just noticed that there is also "*_t" for "::type" like std::conditional_t.

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Peter Kasting

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Feb 21, 2022, 11:08:33 PM2/21/22

to Daniel Cheng, cxx

AFAICT this landed but the text in the markdown still says "[tbd]". Someone want to fix that quick? (Sorry, I'm on vacation and not on a work setup)

PK

On Thu, Jan 6, 2022 at 12:41 PM Daniel Cheng <dch...@chromium.org> wrote:

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Daniel Cheng

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Feb 22, 2022, 1:43:26 AM2/22/22

to Peter Kasting, cxx

Oops, thanks for catching that. https://chromium-review.googlesource.com/c/chromium/src/+/3478828

Daniel

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