[boost] Re: Proposed smart_handle library

From: John Madsen (johnmadsen_usenet_at_[hidden])
Date: 2003-07-21 23:27:09

"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.