Re: Logical Value Of A Pointer
* Kai-Uwe Bux:
James Kanze wrote:
[snip]
(But if I
understand your argument correctly, you're not arguing for the
conversion, but rather that "conditions" can take many different
types, and not just bool. Which sounds like an oxymoron to me.)
That is confusing the definitions of the standard with how one thinks about
language constructs. The implicit conversion are crafted so that
if ( expr ) { ... }
is for all practical purposes equivalent to
if ( expr != 0 ) { ... }
So, one may think about if-clauses as testing for non-zeroness. That the
standard accomplishes this by implicit conversions is immaterial. Also,
that the standard calls the syntactic element involved a "condition" is
immaterial.
It is possible that chess player thinks that a knights move is one step
diagonal followed by an outward one step rook move. Now some rule book
could defined it as a two step rook move followed by a one step rook move
in a perpendicular direction. There will never be any observable
disagreement between the player and the rule book. There is no reason the
player should change his way of thinking.
I think this is like discussing the general issue of # of angels that can fit on
a dog's snout without causing the dog to sneeze.
But anyways, in a broader perspective it is about adopting consistent coding
conventions, and about deviating from such conventions in certain idiomatic cases.
For full consistency, allowing a later change from raw pointer to smart pointer,
one should ideally write e.g.
if( !isZero( p ) ) { ... }
and not as Andrew likes
if( p ) { ... }
or as James and I like
if( p != 0 ) { ... }
or as some have advocated elsewhere,
if( p != nullPtr )
But in reality the effort of using something like 'isZero' will mostly be
wasted: the pointer's type will probably never be changed. And wasted effort is
generally ungood. So upshot is to do what's natural, what one's accustomed to,
unless there are coding guidelines that force some particular way.
Cheers,
- Alf