Re: vector assign

From:
"Alf P. Steinbach" <alfps@start.no>
Newsgroups:
comp.lang.c++
Date:
Sat, 24 May 2008 12:34:56 +0200
Message-ID:
<GJadnVbpyezPcqrVnZ2dnUVZ_vzinZ2d@posted.comnet>
* James Kanze:

On May 24, 1:48 am, acehr...@gmail.com wrote:

On May 23, 3:40 pm, stephen b <ker...@audiospillage.com> wrote:

Hi all, personally I'd love to be able to do something like this:

vector<int> v;
v.assign(1, 2, 5, 9, 8, 7) etc


Checkout Boost's Assign Library. You can do these:

vector<int> v;
v += 1,2,3,4,5,6,7,8,9;


Institutionalized obfuscation, anyone? That statement has a
predefined meaning in C++, without any library, and any code
which changes a predefined meaning should be avoided at all
costs.


I tend to use "<<" for adding things to some logical container.

Like v << 1 << 2 << 3;

Part of reason is that it's easy to implement and difficult to misunderstand.

Of course it's generally inefficient compared to specialized way in each
particular case, but very convenient.

E.g., off the cuff,

   template< typename T, typename U >
   std::vector<T>& operator<<( std::vector<T>& v, U const& u )
   {
       v.push_back( u );
       return v;
   }

I don't think it's worth it or even a good idea to add more features, but it's
easy to do that also, e.g.

   struct Clear {};

   template< typename T >
   std:vector<T>& operator <<( std::vector<T>& v, Clear )
   {
       std::vector<T>().swap( v );
       return v;
   }

enabling things like

   v << Clear() << 1 << 2 << 3;

So on.

Agreed that overloading comma operator is a little bit Evil(TM). :-)

Cheers,

- Alf

--
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