Re: [boost] named template parameters using mpl

From: David Abrahams (dave_at_[hidden])
Date: 2003-01-31 15:46:06

Howard Hinnant <hinnant_at_[hidden]> writes:

> On Friday, January 31, 2003, at 12:54  PM, Jonathan Wang wrote:
>
>> The default features(types) are stored in a
>> type-vector, and we can use boost.mpl to update the
>> default features into use-defined ones, and to
>> extract the updated paramters from type-vector. Then
>> we can use NTPs later. And even can we mix the NTPs
>> and the ordinary paramters, just to use ntp::update2
>> instead of ntp::update.
>
> I've also looked at ntp implementation similar to this
> (but used Loki type lists), and agree that this is a
> neat way to go.  Essentially you just stick the
> defaults onto the end of the type list.  Then if the
> user specifies anything, either by a default tag, a
> named parameter, or a positional parameter, you prepend
> it to the type list.  Then the extraction routine
> simply searches the type list for the first appropriate
> parameter.

That's how my "defaults by type properties" thing works as well.  I
wonder if a single framework could be used to handle both approaches?

-- 
                       David Abrahams
   dave_at_[hidden] * http://www.boost-consulting.com
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