Re: Useless use of smart pointers

From:
Goran <goran.pusic@gmail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Fri, 5 Jun 2009 11:50:59 CST
Message-ID:
<ec006c0a-aba2-467b-8688-ccc10b937faa@v4g2000vba.googlegroups.com>
 From what you describe, it's simple enough that there's no need for
smart pointers. I see no purpose for weak pointers at all, either.
Also (again, from what you describe), your store is better written
using references (that breaks existing code that uses pointers, but a
simple facade can alleviate that):

class ObjStore1 {
public:
     const Obj& get( const std::string& filename );
     ~ObjStore1();
private:
     typedef std::map< std::string, const Obj* > store_type;
     store_type store;
};

const Obj& ObjStore1::get( const std::string& filename )
{
     store_type::const_iterator it = store.find( filename );
     if ( it != store.end() ) {
         return *it->second;
     } else {
         std::auto_ptr< Obj > pObj( new Obj( filename ) );
         store[ filename ] = pObj.get();
         return *pObj.release();
     }
}

Note also that you take unneeded performance hit in get(): you use
find and op[]. That's two searches. You should use lower_bound and
insert to eliminate one.

Goran.

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