Re: [boost] [proto] small breaking change

Subject: Re: [boost] [proto] small breaking change
From: joel falcou (joel.falcou_at_[hidden])
Date: 2010-06-14 02:10:24

Eric Niebler wrote:
> Heck, it's simple enough. I just checked in the fix on trunk. Let me
> know how that works for you.
>   
OK the base case is working now. I just got a last small problem.

If I try to evaluate :

  m = l+k,
  x = x + y;

with the former code given earlier and the latest trunk, the display of 
the evaluation is:

assign(
    terminal(St6vectorIiSaIiEE)
  , plus(
        terminal(St6vectorIiSaIiEE)
      , terminal(St6vectorIiSaIiEE)
    )
)
assign(
    terminal(St6vectorIiSaIiEE)
  , plus(
        terminal(St6vectorIiSaIiEE)
      , terminal(St6vectorIiSaIiEE)
    )
)
comma(
    assign(
        terminal(St6vectorIiSaIiEE)
      , plus(
            terminal(St6vectorIiSaIiEE)
          , terminal(St6vectorIiSaIiEE)
        )
    )
  , assign(
        terminal(St6vectorIiSaIiEE)
      , plus(
            terminal(St6vectorIiSaIiEE)
          , terminal(St6vectorIiSaIiEE)
        )
    )
)
assign(
    terminal(St6vectorIiSaIiEE)
  , plus(
        terminal(St6vectorIiSaIiEE)
      , terminal(St6vectorIiSaIiEE)
    )
)
assign(
    terminal(St6vectorIiSaIiEE)
  , plus(
        terminal(St6vectorIiSaIiEE)
      , terminal(St6vectorIiSaIiEE)
    )
)

where it should have been only :

comma(
    assign(
        terminal(St6vectorIiSaIiEE)
      , plus(
            terminal(St6vectorIiSaIiEE)
          , terminal(St6vectorIiSaIiEE)
        )
    )
  , assign(
        terminal(St6vectorIiSaIiEE)
      , plus(
            terminal(St6vectorIiSaIiEE)
          , terminal(St6vectorIiSaIiEE)
        )
    )
)

Which means that the x = x+y expression is copied and destroyed four 
time despite my "no-eval" policy in the constructor of expr. I assume 
some temporary copy are made which are not captured by my no-eval code 
in nt2::containers::expr.

Did I missed some customization to make subdomain/domain expression be 
captured by reference or should I had some new copy 
constructor/operator= in my expression class in which I have to toggle 
the "no-eval" switch ?