Folly: An open-source C++ library developed and used at Facebook

Re:Folly: An open-source C++ library developed and used at F... by PaulDavisThe1st on Friday January 07, 2022 @03:16PM (#29844165)

interesting case in point. i just learned today that std::variant and boost::variant differ in their:

   1. exception-safety guarantees
   2. real-time safety

2 is caused by 1, because to be exception safe requires a heap allocation, and that's not RT-safe.

Who would want to work in a language where you could not make these choices?

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Re:Folly: An open-source C++ library developed and used at F... by jcelerier on Saturday January 08, 2022 @02:28AM (#29849483)

Boost even has variant2 which comes with another set of design tradeoffs

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Re:Folly: An open-source C++ library developed and used at F... by hn_go_brrrrr on Saturday January 08, 2022 @01:17AM (#29849099)

When does std::variant allocate?

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Re:Folly: An open-source C++ library developed and used at F... by PaulDavisThe1st on Saturday January 08, 2022 @01:23AM (#29849134)

boost::variant will allocate to save state during construction of a new value type, in order to be able to roll back if the constructor throws an exception.

std::variant does not do this.

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Re:Folly: An open-source C++ library developed and used at F... by gumby on Sunday January 09, 2022 @11:05PM (#29870498)

Is std::variant forbidden from doing this per standard or is it simply one (or several) implementations that made this choice?

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