null [re: spec#]

[Daniel Gibson]

Nick Sabalausky schrieb:
> "so" <so at so.do> wrote in message news:op.vlv3iukp7dtt59 at so-pc...
>>> There's no usage of an undeclared variable, but the right-hand-side of 
>>> the
>>> second line uses 'i' before *the programmer* initializes it. Yes, the D
>>> compiler chooses to automatically initialize it, but by doing so it 
>>> silently
>>> creates a bug every time the programmer intends 'i' to start out as 
>>> anything
>>> other than 0. And it's not easily noticed since 0 is a commonly-used 
>>> value.
>>> (Something like 0xDEADBEEF would at least be an improvement (albeit a 
>>> small
>>> one) since at least that would stand out more and likely fail more
>>> spectacularly.)
>> So you want language force you to type either "int x=0;" or "int x=void;".
>> Fair enough and i agree it "might" be a bit better. But you are making it 
>> as it is something so much important.
> 
> I tend to get a bit fired up by it because Walter's reasoning on it being 
> *better* to automatically assume some init value baffles me.
> 

It gives deterministic results/errors.
For example, when your code works when an int is initialized with 0 (but you 
didn't initialize it), it may work most of the time in C and fail randomly. In D 
it will always work. Same thing the other way round.
Or if you do some calculation with an uninitialized int value.. I guess 0 is one 
of the easiest values to spot: on multiplication it creates 0 and on addition it 
doesn't change to value so by looking at the unwanted result of a calculation 
you probably can see the error more easily than on some other value (or even a 
random value, that may create results that look about right).