[Boost-users] Re: composition and arguement binding: what to use: boost::bind vsboost::mpl vs boost::lambda

From: David Abrahams (dave_at_[hidden])
Date: 2005-03-16 09:41:46

Stuart Dootson <stuart.dootson_at_[hidden]> writes:

> On Tue, 15 Mar 2005 11:56:31 -0500, Robert Mathews <rmathews_at_[hidden]> wrote:
>> I've become rather confused about the exact relationship between these
>> libraries.  In particular, boost::mpl seems to contain placeholders and
>> lambda templates just like boost::bind and boost::lambda.
>> 
>> That leds me to wonder if there would be any point to using boost::bind or
>> boost::lambda if you are using boost::mpl? In fact, if boost::mpl is a
>> functional superset of the other two libraries, why not drop those libraries
>> from boost altogether and eliminate the confusion?
>> 
>> Rob.
>> 
>
> boost::mpl performs binding of meta-functions (i.e. binding within the
> compile-time domain), whereas bind and lambda perform binding of
> functions and function objects (i.e. binding within the run-time
> domain).
>
> As far as I can see, Boost.Bind is effectively a subset of
> Boost.Lambda (I may well be wrong, though!). However, if you're using
> an older compiler (such as MSVC6), then using Boost.Lambda can be
> problematic, whereas Boost.Bind works fine.

And unless Boost.Lambda has been updated since I looked, there are
some nice things that Boost.Bind handles automatically, like calling
through smart pointers, that aren't quite so easy with Boost.Lambda.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com