[boost] Re: Re: Boost Array Initialization Technique

From: Neal Becker (ndbecker2_at_[hidden])
Date: 2005-06-01 11:48:18

christopher diggins wrote:

> ----- Original Message -----
> From: "Neal Becker" <ndbecker2_at_[hidden]>
> To: <boost_at_[hidden]>
> Sent: Wednesday, June 01, 2005 8:33 AM
> Subject: [boost] Re: Boost Array Initialization Technique
> 
> 
>> Loïc Joly wrote:
>>
>>> AlisdairM a écrit :
>>>
>>>> Aggregate initialization is an important part of the array concept,
>>>> allowing it to act largely as a plug-in replacement for language
>>>> arrays, with the bonus it can be passed by value as well as by
>>>> reference.  The main drawback here is that we cannot deduce the size of
>>>> a boost::array, as you can with a language array.
>>>
>>>  From my point of view, the main drawback is that in the following code:
>>>
>>> vector<double> v1(6);
>>> array<double, 6> v2;
>>>
>>> v1's content is initialized, v2's content is not. In fact, array is
>>> about the only class I know of that as a default constructor that does
>>> not initialize member data to a legal and documented value. This I
>>> strongly dislike.
>>>
>>> By the way, I also dislike the fact that double d; does not initialize
>>> d, but at least people know that fundamental type do not behave well
>>> when initialization is concerned.
>>>
>>
>> I strongly disagree.  Forcing initialization makes code that is not
>> useful
>> for high performance numerical processing.  When we declare a container
>> of 1000000 elements, we don't want to waste time initializing each,
>> unless we want to.
> 
> 
> I think the best solution in this case is to use an alternative
> "collection" for numerical processing. Using a class intended as general
> purpose array for numerical processing I think would not be a good idea.
> 

I still disagree.  Depending on default initialization is like depending on
init of static variables to 0.  If you really need a special init value, be
explicit and say so.  I see no logic to the default construct of complex to
have 0 value.  The only logic to default construct values I can see is
where there truly is a sensible default for a parameter.