On 02/05/2012 04:17 PM, Jose Armando Garcia wrote:
On Sun, Feb 5, 2012 at 12:57 PM, Timon Gehr<timon.g...@gmx.ch> wrote:
On 02/05/2012 03:53 PM, so wrote:
On Sunday, 5 February 2012 at 14:24:20 UTC, Timon Gehr wrote:
This should work:
#define DOTDOTDOT ...
template<class T> void fun(T a){
if(cond<T>::value) {
auto var = make(a);
DOTDOTDOT;
}else{
auto tmp = make(a);
auto var = make_proxy(tmp);
DOTDOTDOT;
}
}
It won't work.
You now have two scopes and you have to repeat every line after "var"
for both scopes. Now you have to maintain both of them.
You just maintain the macro.
And this grows
exponentially for every new condition you have.
It certainly has limits. I completely agree that C++s generic programming
facilities are severely underpowered.
What I would really like to see in D is:
immutable variable = if (boolean_condition)
{
// initialize based on boolean_condition being true
}
else
{
// initialize based on boolean_condition being false
}
Scala has this and find it indispensable for functional and/or
immutable programming. Yes, I have been programming with Scala a lot
lately. It has a lot of problem but it has some really cool constructs
like the one above. Scala also has pattern matching and structural
typing but that may be asking too much ;).
I am not sure what it would take to implement this in D but I am
thinking we need the concept of a void type (Unit in scala). Thoughts?
immutable variable = (boolean_condition) ? {
// initialize based on boolean_condition being true
}():{
// initialize based on boolean_condition being false
}();
