On Friday, 10 October 2014 at 09:58:54 UTC, Walter Bright wrote:
On 11/27/2011 11:53 AM, deadalnix wrote:
I wonder why struct can't have a default constructor. TDPL
state that it is
required to allow every types to have a constant .init .
Having a .init instead of a default constructor has all kinds
of useful properties:
1. the default object is trivially constructable and cannot fail
2. an easy way for other constructors to not have overlooked
field initializers, so they get garbage initialized like in C++
3. generic code can rely on the existence of trivial
construction that cannot fail
4. dummy objects can be created, useful for "does this compile"
semantics
5. an object can be "destroyed" by overwriting it with .init
(overwriting with 0 is not the same thing)
6. when you see:
T t;
in code, you know it is trivially constructed and will succeed
7. objects can be created using TypeInfo
Default constructors are baked into C++. I can't escape the
impression that the desire for D default constructors comes
from more or less trying to write C++ style code in D.
Bit OT: What is The D code style then? It would be very useful
for those coming from C++ to have a wiki/article on how to
translate C++ idioms and practices to D. I too am writing D code
like I do my C++ and often find myself puzzled (deterministic
d-tors being perfect example). Missing default struct c-tor is
also one of such examples - and adding opCall() feels hacky.
