Re: [Boost-users] [lambda] extending lambda functions

alfC wrote:

Hi Joel,

On Mar 21, 9:49 pm, Joel de Guzman wrote:

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alfC wrote:

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the question is what do I have to do to be able to use the following syntax instead _1 + llnorm(_2) Lambda does not have such a facility.

Ok, I believe you, I will use bind instead for the moment. However I am still puzzled: for example, when boost::lambda defines some operator+ (the one use above) it does indeed what we expect. What is special about operator+ compared to any other user defined (lazy) function defined by the user? (i.e. the lazy function that I want but don't know how to define in the context of Lambda) After all the operator+ above must be a function defined somewhere.

Because there is only a finite number of operators that we need to overload. OTOH, there's an infinite number of functions. In Phoenix, we take care of only a smallish subset related to STL algorithms and containers (e.g. for_each, etc.). It is easy to add more lazy standard functions if there are would be volunteers.

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You can use Phoenix instead. Phoenix (lazy) functions allow you to do that. Phoenix is intended to supercede Lambda. Phoenix has been reviewed and is conditionally accepted into Boost after another mini-review.

I used Spirit a little bit and I recall that Phoenix was part of Spirit or something like that. While we wait for the Phoenix library, would you recommend to use the Phoenix included in Spirit?

Sure, why not? It is a very stable and mature library. Once we deal with the review related matters, there will be some changes, but I don't think it will be drastic. Regards, -- Joel de Guzman http://www.boostpro.com http://spirit.sf.net