Re: [boost] Re: Proposed smart_handle library

From: Gregory Colvin (gregory.colvin_at_[hidden])
Date: 2003-07-21 23:54:29

I'm generally less afraid of automatic conversions than many others, and
dropped them from auto_ptr, and later from shared_ptr, only under 
duress.
I like them for wrapper classes because they make it possible to drop 
the
wrappers directly into existing code that uses the wrapped types.  I 
like
the terseness too, but then I am perverse enough to prefer &*p to 
p.get().

On Monday, Jul 21, 2003, at 22:27 America/Denver, John Madsen wrote:

> "Eugene Lazutkin" <eugene_lazutkin_at_[hidden]> wrote:
>> Inline.
>>
>> "John Madsen" <johnmadsen_usenet_at_[hidden]> wrote in message
>> news:bfd8bo$gca$1_at_main.gmane.org...
>>>
>>> If you can convince most of the people on this list to provide an
>> automatic
>>> conversion, more power to you.  I still maintain that avoiding hard 
>>> to
>> diagnose
>>> errors is worth much more than saving 6 characters of typing.
>>
>> I am not trying to convince anybody in overall goodness of automatic
>> conversion. :-) I am asking question, which is still ignored: what 
>> "hard to
>> diagnose errors" do you envision for smart handles??? Reference to 
>> some
>> dogma would suffice too. ;-)
>>
>>> For a discussion of why user defined conversions are a bad idea (not
>> always,
>>> but most of the time), see More Effective C++, Item 5.
>>
>> I've read it when it was printed. I know author's reasons. And I 
>> agree with
>> most of them. The question is: how do they apply in _this particular 
>> case_?
>>
>
>
> I am not ignoring the question.  The point is that it is hard to guess 
> what
> errors might occur.  I did reference some dogma as well.  I take 
> Meyers' point
> to be that automatic conversions can sometimes produce surprising 
> effects.
> Those effects may result in code that does something other than what 
> it appears
> to do.  Thus, *unless there is a very good reason*, avoid automatic
> conversions.  That is what I did.  Your reason for including them, 
> i.e.,
> avoiding typing, does not strike me as a good one.
>
> John
>
> P.S.  Of course, if you want Scott Meyers on your side in this one, 
> just look
> at Item 9 in the same book, where he does exactly what you're 
> suggesting :-).
> Against his own better judgment IMHO.