Re: [Boost-users] [proto] baby steps learning with proto, proxy object

8 Oct 2010


      On 10/7/2010 2:52 PM, alfC wrote:
<snip>
...
So I guess we can create a proxy of the expression h[x] , "subindex of
historgram with double". The proxy can be used with the syntax to call
either accumulate or increment depending on the application of += or +
+ to the proxy.
The naive implementation is this:
class histogram{
  ...
  private:
  struct proxy_histogram_subscript{
      histogram& self;
      double const& x;
      proxy_histogram_subscript(histogram& self, double const& x) :
self(self), x(x){}
      proxy_histogram_subscript const& operator++()
const{self.increment(x); return *this;}
      bool operator++(int) const{return self.increment(x);}
      bool operator+=(double const& weight) const{return
self.accumulate(x, weight);}
  };
  public:
  proxy_histogram_subscript operator[](double const& x){
      return proxy_histogram_subscript(*this, x);
  }
};
which allows the desired syntax. The question is, can Boost.Proto do
better?
<snip>
Not really, I don't think. What you have is short, simple, and
efficient. I wouldn't mess with it further.

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com