On Mon, 28 Sep 2009 21:43:20 -0400, Jesse Phillips
<jessekphill...@gmail.com> wrote:
On Mon, 28 Sep 2009 16:01:10 -0400, Steven Schveighoffer wrote:
On Mon, 28 Sep 2009 15:35:07 -0400, Jesse Phillips
<jesse.k.phillip...@gmail.com> wrote:
language_fan Wrote:
Have you ever used functional languages? When you develop in Haskell
or SML, how often you feel there is a good change something will be
initialized to the wrong value? Can you show some statistics that show
how unsafe this practice is?
So isn't that the question? Does/can "default" (by human or machine)
initialization create an incorrect state? If it does, do we continue to
work as if nothing was wrong or crash? I don't know how often the
initialization would be incorrect, but I don't think Walter is
concerned with it's frequency, but that it is possible.
It creates an invalid, non-compiling program.
No it doesn't, I'm not referring to null as the invalid state.
float a;
In this program it is invalid for 'a' to equal zero. If the compiler
complains it is not initialized the programmer could fulfill the
requirements.
I am not arguing for floats (or any value types) to be required to be
initialized.
float a = 0;
Hopefully the programmer knows that it shouldn't be 0, but a correction
like this is still possible, the compiler won't complain and the program
won't crash. Depending on what 'a' is controlling this could be very bad.
I'm really not arguing either way, I'm trying to make it clear since no
one seems to be getting Walters positions.
I get his arguments, but I think they are based on an non-analagous
situation. I think his arguments are based on his experience with
compilers or corporate rules requiring what you were saying --
initializing all variables. We don't want that, we just want the
developer to clarify "this variable is initialized" or "this variable is
ok to be uninitialized".
BTW, what is it with people writing
SomeObject foo;
If they believe the compiler should enforce explicit initialization? If
you think an object should always be initialized at declaration don't
write a statement that only declares and don't set a reference to null.
It's more complicated than that. For example, you *have* to write this
for objects that are a part of aggregates:
class SomeOtherObject
{
SomeObject foo; // can't initialize here, because you need to use the
heap, and compiler only allows CTFE initialization.
this()
{
foo = new SomeObject(); // here is where the initialization sits.
}
}
This is ok, but what if the initialization is buried, or you add another
variable to a large class and forgot to add the initializer to the
constructor?
And there *are* cases where you *don't* want to initialize, that should
also be possible:
SomeObject? foo;
If this wasn't part of the proposal, I'd agree with Walter 100%, but it
gives the lazy programmer an easy way to default to the current behavior
(easier than building some dummy object), so given the lazy nature of said
programmer, they are more likely to do this than assign a dummy value.
-Steve
