Re: How widely used are <ext/hash_set> and <ext/hash_map>?

[Joe Buck <Joe dot Buck at synopsys dot COM>]

I wrote:
> > The thread arguing about this has gone on for a while, so I think
> > it's time to gather some data to answer the question of just how bad
> > it will be if we accept the decision to move ext/hash_set and ext_hash_map
> > into a different directory and to deprecate them.
> > 
> > Any of you out there who put out distros or port collections: how many 
> > packages in your distro use these classes?  You can grep for
> > 
> > '# *include *<ext/hash'
> > 
> > I'm particularly interested in the "Debian number", since the package
> > collection is so large.  Other information about use of these classes
> > will be interesting as well.

On Thu, Oct 25, 2007 at 09:52:52PM -0700, Ian Lance Taylor wrote:
> Here is something to look at:
> 
> http://google.com/codesearch?q=%23include+%3Cext%2Fhash&btnG=Search&hl=en&lr=

Thanks, Ian (and thanks, Google).  There are about 400 hits, though I have
no idea how complete the Google codebase is compared to what's in a distro.

Thinks that will need fixing include inkscape, Boost, wxWindows, and
kdevelop, and at least 50 other programs, though it's hard to get a
good count, since the search is by file rather than by program.

I do see that monotone can use either the TR1 unordered containers or
<ext/hash_{map,set}>, but that's the only one I saw.  Lots of programs are
designed to look either for <hash_set> or for <ext/hash_set>, but they
won't look for <backward/hash_set>.  It also appears that some programs
are designed to fall back to <set> or <map> (therefore paying a
performance penalty) if the configure script does not find <hash_set> or
<ext/hash_set>.

Some programs try to isolate the details of where the headers are by
having one header with #ifdefs that, in turn, does the #include of
<ext/hash_{set,map}>, but many others do not.