The Nullity Of strings and Its Meaning

[Jonathan M Davis via Digitalmars-d-learn]

On Sunday, July 9, 2017 1:51:44 PM MDT kdevel via Digitalmars-d-learn wrote:
> > You also shouldn't rely on it returning null for a null input,
> > even when it currently does that.
>
> I assumed that a non-null string is returned for a non-null input.

There are going to be functions that return null rather than an empty slice
of the original array. You really can't rely on getting an empty array
instead of a null one from a function unless the documentation tells you
that. For most purposes, there is no practical difference between a null
array and an empty array, so very little code is written which cares about
the difference. The only place where I would expect a function in a library
to distinguish is if its documentation says that it does (e.g. if returning
null means something specific or if it specifically says that the result is
a slice of the input).

In general, relying on whether a dynamic array is null or not outside of
code that you control or functions that are explicit about what they so with
null is risky business.

Sometimes, I wish that null were not treated as empty, and you were forced
to allocate a new array or somesuch rather than having null arrays just work
- then you could actually rely on stuff being null or not - but that would
also result in a lot more segfaults when people screwed up. The status quo
works surprisingly well overall. It just makes it dangerous to do much with
distinguishing null arrays from empty ones.

- Jonathan M Davis