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From: Beman Dawes (bdawes_at_[hidden])
Date: 2003-10-20 08:05:18

Although I certainly think the library fills a very real need for
additional string algorithms, there are serious problems with the library
as proposed. Since the problems prevent a complete review, I vote that this
library not be accepted.

Here are the serious problems that prevent a complete review:

Two libraries intertwined

There really two libraries here:

-- Some additional (and welcome) low level algorithms, particularly useful
with strings.

-- A framework of Container Traits, Sequence Traits, and iterator_ranges
which can be used to construct algorithmic functions interfaces and
implementation at a slightly higher level than traditional begin, end,
iterator arguments.

Mixing the two together in one review causes me great concern. I'd really
like to evaluate the framework aspect by seeing it applied to the familiar
Standard Library STL algorithms. If the framework isn't beneficial for
those existing algorithms, I'm really not interested in it for strings
alone. Yet all the framework uses in the library deal with the new string

Likewise, I'd like to review the string algorithms separately. As it stands
now, when I try to review one of the string algorithms, I get lost in
issues relating to the framework and can't give the algorithm itself full

Failure to specify foundation algorithms

The foundation of any STL-like algorithm extension library are the
functions which operate on iterators and iterator ranges. If these are
deficient, convenience wrappers only paper-over the problems.

Yet in the string_algo library, the foundation algorithms are placed in
namespace detail and are not documented. Thus it isn't possible to
seriously review them. (Reading the code doesn't count, as far as I'm


The documentation is so short on specifics that it is not possible to
evaluate the library. For example, the "trim" function is specified thus:


    template<typename ContainerT>
      ContainerT &
      trim(ContainerT & Input, const std::locale & Loc = std::locale());



      An input container

      A locale used for 'space' classification

    Remove all leading and trailing spaces from the input. The input
    sequence is modified in-place.

    Returns: A reference to the modified input

The lack of any further specification (such as requirements or concepts)
for ContainerT prevents understanding the limitations of the function. This
same lack of specification for template parameters is pervasive throughout
the library. Likewise, the documentation pervasively fails to specify
preconditions, exceptions which might be thrown, or postconditions.
Specification of effects or returns, where present, tends to be informal
and underspecified. These documentation failures prevent a reviewer from
seriously reviewing the library.

For the iterator_range packaging of two iterators into an object which
provides a container interface, it is particularly important to know the
concepts/requirements on the iterators, because these flow through to the
resulting container. Without any specification or documentation about how
the category of iterator affects the resulting pseudo container, it is hard
to know if this is a worthwhile approach or not.

I believe these big-picture problems need to be addressed before the
libraries can be fully reviewed.


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