On Thursday, 27 February 2020 at 18:58:40 UTC, Walter Bright
wrote:
On 2/27/2020 1:45 AM, Rainer Schuetze wrote:
The string buffer could also be stack allocated or manually
managed with
malloc/free by the string interpolation type.
It's quite a big deal to make that work, and does not address
the inherent inefficiency of it.
printf, for all its faults, is very efficient, and one reason
is it does not require arbitrary temporary storage. Another is
it does not require exception handlers. I, for one, simply
would not use such when printf is available.
It isn't that efficient. There are a lot of implementations
faster than it, and funnily enough they allocate memory, use
exceptions, and RAII.
People often overlook how *expensive* RAII is. Turn exception
handling on and have a look at the generated code.
There was a whole other thread about this, and people found the
assembly generated isn't all that different. Yes throwing
exceptions is expensive, but what you are talking about, the cost
of not throwing them, it really isn't. You are making it out to
be a bigger problem than it actually is. If it caused such a huge
performance hit, then exceptions simply wouldn't be used at all
in C++. But that's not the case.
It's a minor syntactic convenience with an unexpected large and
hidden cost. That's not what D is about.
Leave this at the user's discretion with:
f(format("hello %betty"));
where the user chooses via the format function which method of
handling temporaries he finds appropriate.
There are quite a few places that D has large hidden costs. Hell
GC and any feature or otherwise that uses it is a large and
hidden cost. You can't really say D is not about unexpected large
and hidden costs when it has a GC integrated into quite a few
features that make it invisible.
