[Just found this sitting unsent in my outbox and its still an interesting C++
issue, so:]
> -----Original Message-----
> From: dox...@li...
> [mailto:dox...@li...]On Behalf Of Wagner,
> Victor
> Sent: 08 May 2001 14:16
> To: 'dox...@li...'
> Subject: RE: (off-topic) RE: [Doxygen-users] Documenting IDL
>
>
> I didn't say operator int(), I said operator void* (). There
> is a large
> difference.
When starting this, I deliberately avoided addined an operator that could be
mistakenly read as returning more information than it does - something that
returns 'bool' is unambiguous, even the most neophyte "next new guy to join the
team" isn't going to try and cast it to anything (which sounds a bit rude and
snotty, but it is exactly the sort of thing that has happened).
So far as any other code is concerned, _what_ is this large difference? The only
use for this operator is in a test such as "if (ptr)" and bool seems to fit that
idea quite nicely.
> the problem of 'adding' your own test is that it isn't the same as:
> real pointers
Very true - for example, with 'real pointers' I wouldn't get upset if people
wrote all their functions calls as Fum(MyPointer fred) whereas with ref-counted
pointers, for example, you want to write Fum(const MyPointer& fred). These are
not 'real pointers' and sometimes it is good to be reminded of this (and
sometimes it is bad).
> STL iterators
Well, I admit to not having tried to combine the two (remember, this all started
from old code, VC++2 days, which rather pre-dates a (working) copy of STL being
available). If (when?) it becomes necessary to combine the two, that does not
preclude leaving in 'IsValid()' - after all, to be an iterator you just need to
provide the correct interface and after that you can add anything else you want.
One day, no doubt, the two will coincide, when someone wants to feed one of
these pointers to an STL algorithm, at which time it would be useful to know
what the large difference is between using operator bool() and operator void
*() - does the former stop something working?
Regards,
Stephen Goudge
> -----Original Message-----
> From: Stephen Goudge [mailto:ste...@pi...]
> Sent: Tuesday, 2001 May 08 09:31
> To: dox...@li...
> Subject: (off-topic) RE: [Doxygen-users] Documenting IDL
>
> [deleted]
>
> Ah, the number of problems trying to do that caused me :-(
>
> I did originally have an operator int() that could be used in
> if-statements,
> which worked fine using VC++2 through to VC++4; then a client
> bought VC++5
> and
> it became ambiguous (I forget the precise reason why), so everything
> switched to
> IsValid() from then on.
>
> I would be tempted nowadays to try and hid IsValid(), but I take the
> attitude
> that if something was done because one compiler needed it
> (and the results
> are
> still legal) then keep it in, because the code will be used
> on a.n.other
> compiler next week, or the week after...
>
> Even with a decent compiler, there is the vexed question of
> what the cast
> operator should be casting _to_ - you don't really want to
> return another
> pointer type, as that looks too much like you're providing a
> backdoor. These
> days, 'bool' would be a reasonable choice (now that the
> compilers actually
> support 'bool'). The best choice would be the mythical
> 'logical' type that
> 'if',
> 'while' etc use, but that isn't available :-(
>
> Stephen Goudge
>
>
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