Re: [Boost-users] [phoenix][lambda] lambda to phoenix translation: get arguments from expression

Subject: Re: [Boost-users] [phoenix][lambda] lambda to phoenix translation: get arguments from expression
From: Joel de Guzman (joel_at_[hidden])
Date: 2010-05-29 07:01:54

On 5/29/2010 3:48 PM, alfC wrote:
>>> with boost.lambda I could extract the different components (Lambda and
>>> the actual value stored by value<double>) from f_expr as:
>>> get<0>(f_expr.args)  //for lambda
>>> and
>>> get<1>(get<1>(f_expr.args).args) //for lambda
>>
>>> what is the equivalent for Boost.phoenix?,
>
>> Check out the extension mechanism (somewhere near the end) where this is
>> documented. See composites. Essentially, while lambda uses tuples, phoenix
>> uses fusion containers -- more or less the same, but with more horsepower
>> (i.e. algorithms and iterators).
>
> I read that part many times but I couldn't realize how to apply it to
> this case.
> I ended up calling
>
> actor<LambdaExp>(at_c<0>(f_expr))
> actor<value<double>  >(at_c<1>(at_c<1>(f_expr)))(), //or
> at_c<1>(at_c<1>(f_expr)).val
>
> seems to work so far (is there a make_actor?)
> I don't know if overall is the best solution.

Either works fine.

Regards,
-- 
Joel de Guzman
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