Re: [boost] Giving names to formal parameters of lambda expressions: a named placeholder trick.

From: Giovanni Piero Deretta (gpderetta_at_[hidden])
Date: 2008-04-02 13:11:51

On Wed, Apr 2, 2008 at 6:01 PM, shunsuke <pstade.mb_at_[hidden]> wrote:
> Giovanni Piero Deretta wrote:
>  >>  BTW, everything must be function-call to support result_of.
>  >
>  > What do you mean exactly with "everything must be function call?".
>
>  result_of<T_lambda(T1)>::type r = lambda(t1); // ok, result_of compatible.

This wouldn't compile in my model, you can't call 'lambda' using
operator() (well, I plan to support
scoped variables a-la phoenix one day, but for the moment it simply
doens't compile).

>  ??? r = lambda[t1];

result_of<T_lambda(T1)>::type r = lambda[t1]

might work just fine, but maybe overloading result_of is not nice.
What about:

protected<t1> r = lambda[t1]

> [...]
>  >>  I tend to hesitate to use result_of/return_of without function-calls.
>  >
>  > Again, what do you mean exactly? And why do you esistate? I'm
>  > evaluating egg design, so these answers would be very valuable.
>
>  E.g.
>    result_of<F(T1)>::type s;
>
>  result_of is a trait which extracts return type of function-calls,
>  but s is default-constructed without function-calls.

Well, what is the problem? As long as there is no bind-like function
in there which requires passing closure parameters, it should be fine.
I agree that it might be confusing initially.

-- 
gpd