On 30/04/12 12:27, Manu wrote:
On 30 April 2012 10:32, Don Clugston <[email protected]
<mailto:[email protected]>> wrote:
On 29/04/12 20:08, Manu wrote:
On 29 April 2012 18:50, Don <[email protected]
<mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
On 28.04.2012 20:47, Walter Bright wrote:
Andrei and I had a fun discussion last night about this
question. The
idea was which features in D are redundant and/or do not add
significant
value?
A couple already agreed upon ones are typedef and the
cfloat,
cdouble
and creal types.
What's your list?
* The >>> operator, which does nothing except introduce bugs (It
does NOT perform an unsigned shift).
What does it do? I use this all over the place, I assumed it
worked...
maybe I have bugs?
It works only for two types: int and long.
For everything else, it is identical to >>
So for short and byte, and in generic code, it's ALWAYS a bug.
O_O
Is that intentional? Or is it... a bug?
I smiled when I saw >>> in the language, I appreciate its presence. It's
not necessary, but it cuts down on some ugly explicit casting (which
theoretically makes generic code simpler).
It's not a bug, it's a design flaw. The buggy behaviour is explicitly
tested in the test suite.
The problem is that the C promotion rules also apply, just as for >> and
<<. But they are fundamentally incompatible with unsigned shift.
So short and byte get promoted to int *by sign extension*,
then the int gets an unsigned shift.
Which means that the short or byte gets a signed shift instead of an
unsigned one.
I used to use >>> in my code, because as you say, it is a nice idea, but
after having a few bugs with short, and working out what the semantics
actually were, I suddenly realized it was a landmine, and I removed
every instance of it from my code.
(cast(ulong)x) >> 3 is safer than x >>> 3, unfortunately.
