on Fri Mar 28 2008, Steven Watanabe <watanabesj-AT-gmail.com> wrote:
AMDG
Giovanni Piero Deretta wrote:
That is, something like this is actually possible:
void foo () { int i = lambda // introduce formal parameter names [ _<class left>(), _<class right>() ] // now use them! [_<left>() + _<right>()] // actual parameters values ( 10, 20 ); }
The _<...>() looks a bit clumsy, but it might be actually usable.
I'd rather not use _. arg sound better. lambda<class left, class right>(arg<left>() + arg<right>())
lambda<args(class left, class right)>(arg<left>() + arg<right>()) I actually like the short nondescriptive names. It's very rare that the semantic information in a descriptive name is more valuable than the syntactic economy of the existing syntax. Just compare the above to: _1 + _2. Which do you find clearer? When the lambda expression is complicated enough that having real names is actually a win, I am usually inclined to write a separate, named function (object), anyway.
Wow. This is awesome. You'd probably better reference the standard (3.3.1/5) since most people will look at this and be surprised to find that it's legal. (I certainly was)
Not so fast. It's legal outside a function, but inside a function "class A" refers to a local class of the function, which isn't a legal template parameter. You might try the following at http://www.comeaucomputing.com/tryitout/ template <class T> struct x{}; template <class T> void f() { x<class A> y; } -- Dave Abrahams Boost Consulting http://boost-consulting.com