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

On Tue, Jan 3, 2017 at 3:48 PM, Christof Donat wrote:

Hi,

Am 03.01.2017 15:23, schrieb Olaf van der Spek:

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On Tue, Jan 3, 2017 at 3:16 PM, Christof Donat wrote: The extra parentheses and the .str() part are annoying.. same goes for boost::format.

I see. For me that is not a big issue, but people are different.

I think the language still doesn't allow temporaries to bind to mutable& so we might've cheered too soon.. :(

...

How about this one?

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

Uh. How does that work with

std::cout << "Error "s << 47;

Will that be

(std::cout << "Error "s) << 47;

or

std::cout << ("Error "s << 47);

We've got rules for that.. http://en.cppreference.com/w/cpp/language/operator_precedence

Also I'd expect a std::string to behave like a stream then and try to use e.g. manipulators. Maybe that would be acceptable with a different operator. e.g. like in SQL:

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

Now this is explicit:

std::cout << "Error "s || 47; // versus

Why would you want to combine << for ostream and string? Just use the ostream one in both cases. I think << is quite elegant. -- Olaf