Jonathan M Davis wrote:
No. You always have a bug if you don't initialize a variable to
the value that
it's supposed to be. It doesn't matter whether it's 0, NaN,
527.1209823, or
whatever. All having a default value that you're more likely to
use means is
that you're less likely to have to explicitly initialize the
variable. It has
to be initialized to the correct value regardless.
Yes, I'm in favor of default values. That's not my argument here.
I'm saying it makes more sense to have the default values be
_usable_ (for convenience) rather than designed to catch
(**cause**) bugs.
And if you're in the habit
of always initializing variables and never relying on the
defaults if you can
help it,
That seams like a very annoying habit requirement for a languages
with a focus on "modern convenience". What's more bug prone, I
think, is forcing developers to remember that unset floats
(specifically) will cause bugs while it's neighboring int works
perfectly without a explicit value.
then the cases where variables weren't initialized to what they
were
supposed to be stand out more.
Usable defaults don't need to stand out because they're usable
and deterministic. If you want to make sure a constructor/method
produces expected results, unittest it.. it makes more sense to
catch errors at compile time anyways.
D's approach is to say that
it's _still_ a bug to not initialize a variable, since you
almost always need
to initialize a variable to something _other_ than a default.
Not always, but that's besides the point. The point is that in
the places where you do want zero values (Vector/Matrix/etc,
Polygon structs, counters, etc..) it's better to have consistent
expected behavior from the default value. Not some value that
causes runtime bugs.
I don't see how it's an
issue, since you almost always need to initialize variables to
something other
than the default, and so leaving them as the default is almost
always a bug.
To me, it's not a huge issue, only an annoyance. However I
wouldn't underestimate the impact of bad marketing. When people
are trying out the language, and they read "variables are
defaulted, not garbage" do you think they're going to expect ints
and floats to work in different ways?
And it doesn't cause bugs to default value types to zero. I have
enough experience with C# to know that it doesn't. All it does is
make the language more consistent.
The only point of dispute that I see in general is whether it's
better to rely
on the default or to still explicitly initialize it when you
actually want the
default.
This sounds like an argument for C++. Explicit declaration isn't
a guard against bugs, you'll still be hunting through code if
something is incorrectly set.
The fact of the matter is default initialization _does_ happen in
code, no matter how philosophically correct "always explicitly
define value" might be. Unless that's enforced, it can and should
be expected to happen. That given, it's more convenient to have
consistent value type behavior. Float is a Value type and
shouldn't be subjective to the security concerns of Reference
types.
Regardless, the _entire_ reason for default-initialization in D
revolves
around making buggy initializations deterministic and more
detectable.
The same way string, and int are defaulted to usable values,
float should be as well. Catching code that works with null
pointers is one thing. Working with a value type without
requiring the programmer have deeper knowledge about D's
asymmetrical features is another.
If D doesn't accommodate entering Laymen, how does it expect to
gain popularity in any major way? Efficiency puts D on the map,
convenience is what brings the tourists.
I'm not trying to convince you that the sky is falling because I
disagree with D's direction with floats.. just if the goal is to
increase D's popularity, little things may turn heads away
quicker than you think. My original post was inspired by me
showing my D code to another C# guy earlier, and coming up with
poor explanations as to why floats where required to be defaulted
in my math lib. His reaction what along the lines of my first
post.
