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March 06, 2009
Re: Null references (oh no, not again!)
> > I call it my billion-dollar mistake. It was the invention of the null
> > reference in 1965. [...] This has led to innumerable errors,
> > vulnerabilities, and system crashes, which have probably caused a
> > billion dollars of pain and damage in the last forty years.
> 
>   -- Sir Charles Hoare, Inventor of QuickSort, Turing Award Winner
> 
> > * Accessing arrays out-of-bounds
> > * Dereferencing null pointers
> > * Integer overflow
> > * Accessing uninitialized variables
> >
> > 50% of the bugs in Unreal can be traced to these problems!

I doubt that blunt non-null forcing will solve this problem. If you're forced to use non-null, you'll invent a means to fool the compiler, some analogue of null reference - a stub object, which use will result into the same bug, with the difference that application won't crash immediately, but will behave in unpredictable way, at some point causing some other exception, so eventually you'll get your crash. Profit will be infinitesimal if any.
March 06, 2009
Re: Null references (oh no, not again!)
"Kagamin" <spam@here.lot> wrote in message 
news:goqoup$jta$1@digitalmars.com...
>> > I call it my billion-dollar mistake. It was the invention of the null
>> > reference in 1965. [...] This has led to innumerable errors,
>> > vulnerabilities, and system crashes, which have probably caused a
>> > billion dollars of pain and damage in the last forty years.
>>
>>   -- Sir Charles Hoare, Inventor of QuickSort, Turing Award Winner
>>
>> > * Accessing arrays out-of-bounds
>> > * Dereferencing null pointers
>> > * Integer overflow
>> > * Accessing uninitialized variables
>> >
>> > 50% of the bugs in Unreal can be traced to these problems!
>
> I doubt that blunt non-null forcing will solve this problem. If you're 
> forced to use non-null, you'll invent a means to fool the compiler, some 
> analogue of null reference - a stub object, which use will result into the 
> same bug, with the difference that application won't crash immediately, 
> but will behave in unpredictable way, at some point causing some other 
> exception, so eventually you'll get your crash. Profit will be 
> infinitesimal if any.

The idea is that non-null would not be forced, but rather be the default 
with an optional nullable for the times when it really is needed.
March 06, 2009
Re: Null references (oh no, not again!)
Nick Sabalausky wrote:
> "Kagamin" <spam@here.lot> wrote in message 
>> I doubt that blunt non-null forcing will solve this problem. If you're 
>> forced to use non-null, you'll invent a means to fool the compiler, some 
>> analogue of null reference - a stub object, which use will result into the 
>> same bug, with the difference that application won't crash immediately, 
>> but will behave in unpredictable way, at some point causing some other 
>> exception, so eventually you'll get your crash. Profit will be 
>> infinitesimal if any.
> 
> The idea is that non-null would not be forced, but rather be the default 
> with an optional nullable for the times when it really is needed. 


This is interesting. I wonder what the practical result of non-null as 
default will be. Do programmers bother to specify nullable when needed, 
or will they "try to do the [perceived] Right Thing" by assigning stupid 
default values?

If the latter happens, then we really are worse off than with nulls.

Then searching for the elusive bug will be much more work.
March 06, 2009
Re: Null references (oh no, not again!)
"Georg Wrede" <georg.wrede@iki.fi> wrote in message 
news:gor5ft$1d6c$1@digitalmars.com...
> Nick Sabalausky wrote:
>> "Kagamin" <spam@here.lot> wrote in message
>>> I doubt that blunt non-null forcing will solve this problem. If you're 
>>> forced to use non-null, you'll invent a means to fool the compiler, some 
>>> analogue of null reference - a stub object, which use will result into 
>>> the same bug, with the difference that application won't crash 
>>> immediately, but will behave in unpredictable way, at some point causing 
>>> some other exception, so eventually you'll get your crash. Profit will 
>>> be infinitesimal if any.
>>
>> The idea is that non-null would not be forced, but rather be the default 
>> with an optional nullable for the times when it really is needed.
>
>
> This is interesting. I wonder what the practical result of non-null as 
> default will be. Do programmers bother to specify nullable when needed, or 
> will they "try to do the [perceived] Right Thing" by assigning stupid 
> default values?
>
> If the latter happens, then we really are worse off than with nulls.
>
> Then searching for the elusive bug will be much more work.

Interesting point. We should probably keep an eye on the languages that use 
the "Foo" vs "Foo?" syntax for non-null vs nullable to see what usage 
patterns arise. Although, I generally have little more than contempt for 
programmers who blindly do what they were taught (by other amateurs) is 
usually "the right thing" without considering whether it really is 
appropriate for the situation at hand.

Although I would think that there must be plenty of examples of things we 
already use that could make things worse if people used them improperly.
March 06, 2009
Re: Null references (oh no, not again!)
Nick Sabalausky wrote:
> "Georg Wrede" <georg.wrede@iki.fi> wrote in message 
> news:gor5ft$1d6c$1@digitalmars.com...
>> Nick Sabalausky wrote:
>>> "Kagamin" <spam@here.lot> wrote in message
>>>> I doubt that blunt non-null forcing will solve this problem. If you're 
>>>> forced to use non-null, you'll invent a means to fool the compiler, some 
>>>> analogue of null reference - a stub object, which use will result into 
>>>> the same bug, with the difference that application won't crash 
>>>> immediately, but will behave in unpredictable way, at some point causing 
>>>> some other exception, so eventually you'll get your crash. Profit will 
>>>> be infinitesimal if any.
>>> The idea is that non-null would not be forced, but rather be the default 
>>> with an optional nullable for the times when it really is needed.
>>
>> This is interesting. I wonder what the practical result of non-null as 
>> default will be. Do programmers bother to specify nullable when needed, or 
>> will they "try to do the [perceived] Right Thing" by assigning stupid 
>> default values?
>>
>> If the latter happens, then we really are worse off than with nulls.
>>
>> Then searching for the elusive bug will be much more work.
> 
> Interesting point. We should probably keep an eye on the languages that use 
> the "Foo" vs "Foo?" syntax for non-null vs nullable to see what usage 
> patterns arise. Although, I generally have little more than contempt for 
> programmers who blindly do what they were taught (by other amateurs) is 
> usually "the right thing" without considering whether it really is 
> appropriate for the situation at hand.
> 
> Although I would think that there must be plenty of examples of things we 
> already use that could make things worse if people used them improperly. 

An interesting thought occurred to me just now. IIRC, Walter's argument 
to always zeroing memory at allocation, was to give "sensible starting 
values" and to "more easily see if data is uninitialised".

If assignment before use is compulsory, then we don't need to zero out 
memory anymore. This ought to speed data intensive tasks up.
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