Boost Users :
Subject: [Boost-users] [fusion] mutable transform
From: David Sankel (camior_at_[hidden])
Date: 2009-05-07 10:21:10
I'm using boost fusion to do some interesting robotics work. This has
come up on the list before, but I'd like to point out my scenario
where a mutable transform function would be useful.
I'm writing a generic interface generator for various datatypes. For a
given instance of the type, the interface generator return a widget
that can modify the instance.
I'd like my implementation for map types to look like this:
for_each( transform( mapInstance
, bind( Layout::addWidget, layout, _1 )
It has a very nice separation of concerns: 1) the "transform toWidget"
function, and 2) the "for_each addWidget" which acts much like a fold.
However, my toWidget function requires a non-const reference so this
doesn't work without a hacky cast to remove the const.
Hackery aside, the only way I know how do to this is using a for_each
who's function argument explicity does both the conversion to a widget
(with toWidget()) and the folding to the layout. Those two concepts
seem separate to me.
Maybe there's a better way or maybe I'm not understanding the
drawbacks of exposing a mutable transpose function.
-- David Sankel Sankel Software www.sankelsoftware.com
Boost-users list run by williamkempf at hotmail.com, kalb at libertysoft.com, bjorn.karlsson at readsoft.com, gregod at cs.rpi.edu, wekempf at cox.net