On Wednesday, 19 September 2012 at 11:51:13 UTC, monarch_dodra
wrote:
The biggest issue with not having a no-arg constructor can
easilly be seen if you have ever worked with a "Reference
Semantic" semantic struct: A struct that has a pointer to a
payload. Basically, a class, but without the inherited Object
polymorphism.
This means that you still have a class object. What is design
behind inserting class into the structure for the sake of
escaping from classes?
These are hard to work with, both for the user and the
implementer: They either use auto-intialization, making EVERY
CALL start with "ensure initialied" (costly for ranges). Either
that, or they need to be explicitly initialized. Or a mix of
both, and a source of bugs and frustration in phobos.
If you know initialize values at compile time, you can use them.
If not, you can overload opCall to make custom initialization at
runtime. Yes, it doesn't help to initialize structures which are
created like "S s;" - but that how structures work: they are
lightweight objects in some matter of speaking and if somebody
wants to call some functions even in such cases, he probably
needs to rethink the design.
HOWEVER, and in contrast to classes, it is surprising that
"auto d = S();" and "auto pd = new S();" does not create an
initialized reference semantic struct. It is a bare minimum to
give a user the ability to allocate & initialize in a single
call...
Indeed, they are initialized.
What is very interesting to note above (IMO), is that the
language provides no less than THREE syntaxes to allocate a
non-constructed S, two of which can be used with auto:
*Explicit typing (a)
*For stack: S.init (c), parenthesis (d)
*for new: without parenthesis (pb), with parenthesis (pd)
Which "construction" do you refer?
