Re: [Boost-users] [Fusion] Views of Associative Sequences

Subject: Re: [Boost-users] [Fusion] Views of Associative Sequences
From: Christopher Schmidt (mr.chr.schmidt_at_[hidden])
Date: 2009-10-15 15:42:47

James Knight schrieb:
> I'm trying to find a solution to the following problem.  If I have an 
> associative sequence such as a fusion::set
> and I make a filter view of it, the view is not a model of an 
> associative sequence and does not support the
> has_key and at_key functions.  I can use fusion::as_set on the view to 
> get an associative sequence again, but
> this doesn't really have the effect I want as it results in a set 
> holding copies of the original data whereas the
> view referenced the original data.  Example below.
> 
> Would it be possible to create a view which supported the associative 
> sequence interface?   Any suggested alternative approaches?
> 
> Thanks
> Nate

There is already a feature request for associative views (ticket 3473). 
I will get down to it once I am granted write access to the trunk.
For now you could use my c++0x port of fusion. It correctly preserves 
the category of the underlying sequence's for all views.
The port is fully backwards compatible, in terms of both features and 
compiler (non-0x compiler are supported).
You can find the code in the sandbox (/sandbox/SOC/2009/fusion/).

-Christopher