Re: [boost] Assign V2 - first impression

Subject: Re: [boost] Assign V2 - first impression
From: Simonson, Lucanus J (lucanus.j.simonson_at_[hidden])
Date: 2011-06-24 16:33:19

er wrote:
>> Now if you want to repeat the operation of inserting the element f(
>> x ), I'm not sure how you do that with Range, but with V2, after
>> learning the syntax, it's relatively straightforward:
>> 
>> ( put_front<1>( cont ) % ( _data = f ) % ( _repeat = n ) )( 1, 10,
>> 100, 1000 ); 
>> 
> 
> This was suggested, which is probably the best:
> 
> push_front<1>( cont ,  _data = f, _repeat = n )( 1, 10, 100, 1000 );
> 
> More generally,
> 
> // Fixed arity:
> push_front<I>( cont ,  options... )( a1,...,aI,...,z1,...,zI );
> 
> // Variadic
> push_front( cont ,  options... )( args1 )...( argsn );
> 
> where in each case (fixed and variadic), options... modify the
> semantics 
> of the subsequent calls to operator().

Can we change the name of _data to something like _filter?  Also, I don't like the pre and post _ names in the interface.  If you want to use a convention related to pre and post _ in the implementation details that's fine, but I don't think it is appropriate in the interface.  If you use boost.parameter I think you would get a post _ charater, I believe, so having both pre and post _ for different reasons seems confusing.

Also, it would be nice to have iterator pair and range be acceptable alternatives to the fixed arity and variadic options shown above.  I realize that would require some SFINAE, but I think being able to consistently initialize containers and then mix the forms would be a big plus.

char* cstr[] = "Hello world!";
std::vector<char> chrs;
push_back( chrs ,  filter = to_upper )( cstr, cstr+5 )( '\0' );

chrs contains a null terminated string "HELLO".

There is then a whole area of treating std::string like a container by specializing some of your library interfaces that would really be handy.

Regards,
Luke