[Boost-users] [string_algo] new flavour of xxx_copy algorithms

From: Yuval Ronen (ronen_yuval_at_[hidden])
Date: 2005-04-02 16:44:31

Hi.

Many algorithms in the string-algo library have 3 versions (I'll take
to_upper as an example):
1. In-place modification which takes a SequenceT by ref:
    template<typename MutableCollectionT>
    void to_upper(MutableCollectionT &);
2. Copy version which takes a SequenceT by const ref, and returns SequenceT:
    template<typename SequenceT>
    SequenceT to_upper_copy(const SequenceT &);
3. Copy version which takes a const ref CollectionT and an
OutputIteratorT and the OutputIteratorT after using it:
    template<typename OutputIteratorT, typename CollectionT>
    OutputIteratorT to_upper_copy(OutputIteratorT, const CollectionT &)

I believe there's room for another version - something that takes a 
const ref CollectionT, and returns a copy in a SequenceT:

template<typename SequenceT, typename CollectionT>
SequenceT to_upper_copy(const CollectionT &);

The benefits are ease of use combined with performance. IMO, a common
scenario is to perform a copy algorithm on a char* string, and returning
  it as a std::string. Such a thing would be easily done with the
proposed extension as:

std::string str = to_upper_copy<std::string>("something");

As it is now, I either have to make additional copy (if I use the
in-place modification version or the SequenceT copy version), or handle
the std::string size my self (if I use the OutputIteratorT version). The
new version will allow me to do it elegantly and efficiently. The
problem is that it probably can't be an overload of to_upper_copy
because it has the same number of arguments as one of the existing
overloads, so it will have to have a different name :-(

Thanks,
Yuval