Re: [boost] Variadic append for std::string

On 01/03/17 17:23, Olaf van der Spek wrote:

On Tue, Jan 3, 2017 at 3:16 PM, Christof Donat wrote:

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Hin

Am 03.01.2017 14:20, schrieb Olaf van der Spek:

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On Tue, Jan 3, 2017 at 2:19 PM, Christof Donat wrote:

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Am 01.01.2017 00:21, schrieb Andrey Semashev:

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throw std::runtime_error(format(std::string()) << "Error " << 47);

How would that differ from

throw std::runtime_error((std::ostringstream{} << "Error " << 47).str());

Simpler syntax, better performance

I see the chances for better performance, but for the syntax I don't really see any remarkable improvements.

The extra parentheses and the .str() part are annoying.. same goes for boost::format.

How about this one?

throw std::runtime_error("Error "s << 47);

Well, if we're using UDLs, we might as well use my `format` proposal or a stream or Boost.Format behind the scene. throw std::runtime_error("Error "fmt << 47); throw std::runtime_error("Error "strm << 47); throw std::runtime_error("Error %d"fmt % 47); Each of the UDL operators would create a wrapper that implements formatting and is convertible to std::string. No need to infect std::string itself with formatting.