Re: [boost] [conversion] try_lexical_cast and 200$

Antony Polukhin wrote:

* `try_lexical_cast` must be added or not?

The motivation given is convincing. "At Facebook we've seen many instances of programs that call lexical_cast in a try/catch. In cases where the parsing is expected to fail (eg, an argument could be an int or a date) we frequently see extremely poor performance in multithreading. GCC is known to have poor multithreaded exception handling gcc.gnu.org/ml/gcc/2013-05/msg00253.html" Even without the performance argument, seeing repeated occurrences of calling a function in a try block is a strong hint that the function perhaps ought to not report the error via an exception.

And if yes, what signature is preffered:

bool try_lexical_cast(Out&, const In&) bool try_lexical_cast(const In&, Out&) boost::optional<Out> try_lexical_cast(const In&)

bool try_lexical_cast(const In&, Out&), I'd say. optional<> is cute because you can use if( auto x = try_lexical_cast<Out>(in) ), but not very convenient for the common case of try_lexical_cast(in1, out1) && try_lexical_cast(in2, out2).