On Sunday, 19 April 2015 at 08:05:46 UTC, Jonathan M Davis wrote:
On Friday, April 10, 2015 09:27:55 w0rp via Digitalmars-d wrote:
I think it's worth changing this.
if (arr)
translating to
if (arr.length == 0)
Is immediately obvious for anyone coming from at least a Python
background. I have implemented my own hashmaps in a similar
way.
For my maps, the length is stored in the map so it can be
retrieved in O(1) time, and cast(bool) results in map.length ==
0. (This extends also to empty sets.)
If we need a deprecation path, we can do it. We just warn about
if (arr) for a while, so you are told to use if(arr.length ==
0)
or if (arr.ptr is null) for a while, then we change the
behaviour
in another release.
I agree with the change, because the current behavior is
error-prone.
However, I'd just as soon leave if(arr) as illegal so that
there's no
confusion over it later. Just because one set of folks think
that if(arr) is
clearly equivalant to if(arr.length != 0) doesn't mean another
set of folks
will - especially if it's based on what other languages are up
to. For
instance, while python folks might think that it would be
intuitive if
if(arr) were equivalent to if(arr.length != 0), the C folks
would think that
the current behavior of it being equivalent to if(arr is null)
would be more
intuitive, since they're used to thinking of arrays as
pointers. By simply
forcing folks to be explicit and say if(arr.length != 0) or
if(arr is null),
we avoid the problem entirely.
- Jonathan M Davis
Unfortunately it also disables this very useful idiom:
if(auto name = getName())
I.e. declaration and conditional in one.
