On 11/06/2010 12:41 AM, Walter Bright wrote:
Denis Koroskin wrote:
On Fri, 05 Nov 2010 23:44:58 +0300, Walter Bright
<newshou...@digitalmars.com> wrote:
To eliminate null pointers is the same as shooting the canary in your
coal mine because its twitter annoys you.
I'm tired of pointing out that NO ONE is talking about eliminating
null pointers, but rather extending an existing type system to support
non-nulls. Your hate towards non-nullables comes from misunderstanding
of the concept.
Consider non-nullable type T:
T[] a = new T[4];
... time goes by ...
T[1] = foo;
T[3] = bar;
... more time goes by ...
bar(T[2]);
In other words, I create an array that I mean to fill in later, because
I don't have meaningful data for it in advance. What do I use to default
initialize it with non-nullable data? And once I do that, should
bar(T[2]) be an error? How would I detect the error?
In general, for a non-nullable type, how would I mark an instance as not
having meaningful data?
For example, an int is a non-nullable type. But there's no int value
that means "no meaningful value", and this can hide an awful lot of bugs.
I'm not sure at all that non-nullable types do more than make easy to
find bugs much, much harder to find.
I tried to find a good analogy but failed, so I'll just say that in the
case you presented you would obviously not use a non-nullable type. As,
you know, you wanted nulls in the array.
We're using signalling nans to get rid of the null-ish thing for floats,
as well.
