Re: [boost] determining if an object is faster to pass by value or const reference

From: Michael Marcin (mike.marcin_at_[hidden])
Date: 2008-07-03 21:12:36

Michael Marcin wrote:
> Alex MDC wrote:
>> Have a look at the Call Traits library, in particular "param_type".
>>
> 
> Never noticed that library. Thanks I'll have a look.
> 

The documentation makes no mention of allowing extension for user 
defined types. It in fact has a table which clearly states that 
param_type is a const reference for all user defined types.

In a specific case I was working on a 3d renderer that we used for a 
mobile project where we used a templated fixed point class. There were 
some low level functions that worked on a typename Real which used pass 
by const reference because cheap copy was not a requirement of our Real 
concept. This project happened to only be using this fixed point type 
which was a wrapper over int. We branched the code and changed the 
functions to pass by value. This resulted in a measurable performance 
increase.

I would like to take classes like this and specialized param_type for 
them but the documentation for this library doesn't seem to allow for that.

Thanks,

Micahel Marcin