On 04/19/2007 03:54 AM, Larry Evans wrote:
On 04/18/2007 01:06 PM, Eric Niebler wrote:
Larry Evans wrote:
[snip]
I've just encounted a need for something like this. For example, if you have a list of types for which you want to apply the or_ to, however, that list must by calculated, then the only way to apply or to it is with a fold operation. Since mpl::fold takes an argument represening the initial state, this would naturally be proto::or_<> in case you want to proto::or_ together a list of types.
<snip>
Interesting. In order for this to work, proto::or_ would need to be an extensible mpl sequence, right?
[snip]
No. The input to fold has to be; however, the output produced doesn't. [snip] I think the output could be adapted to conform to mpl sequence requirements. I've got a fold_seq template which does this, in case you're interested.