• ZombineDev (41/41) Feb 03 2016 C++11 allows you to capture a local variable explicitly by value.
• ZombineDev (4/46) Feb 03 2016 I think these two links, more or less, answer my question:
• Basile B. (30/33) Feb 03 2016 Another approach:
• =?UTF-8?Q?Ali_=c3=87ehreli?= (11/14) Feb 03 2016 I find it more readable to give a name like makeClosure():

ZombineDev <valid_email he.re> writes:

C++11 allows you to capture a local variable explicitly by value.

What is the simplest way to make code below print "0 1 .. 9", 
like the C++ version does?

D version:
```
import std.stdio;

void main()
{
     alias F = void delegate();
	
     F[] arr;
	
     foreach (i; 0 .. 10)
         arr ~= { write(i, " "); };
			
     foreach (f; arr)
         f();
}
```
Prints: 9 9 9 9 9 9 9 9 9 9


C++ version:
```
#include <iostream>
#include <functional>
#include <vector>
using namespace std;

int main()
{
     using F = function<void()>;

     vector<F> arr;

     for (auto i = 0; i < 10; ++i)
         arr.push_back([=]() { cout << i << " "; });

     for (auto f : arr)
         f();
}
```
Prints: 0 1 2 3 4 5 6 7 8 9

One stupid solution is to replace `0 .. 10` with staticIota!(0, 
10), which would unroll the loop at CT, but I want something more 
general that would me allow me to capture the values of a range 
while iterating over it at run-time.

ZombineDev <valid_email he.re> writes:

On Wednesday, 3 February 2016 at 18:03:24 UTC, ZombineDev wrote:
 C++11 allows you to capture a local variable explicitly by 
 value.

 What is the simplest way to make code below print "0 1 .. 9", 
 like the C++ version does?

 D version:
 ```
 import std.stdio;

 void main()
 {
     alias F = void delegate();
 	
     F[] arr;
 	
     foreach (i; 0 .. 10)
         arr ~= { write(i, " "); };
 			
     foreach (f; arr)
         f();
 }
 ```
 Prints: 9 9 9 9 9 9 9 9 9 9


 C++ version:
 ```
 #include <iostream>
 #include <functional>
 #include <vector>
 using namespace std;

 int main()
 {
     using F = function<void()>;

     vector<F> arr;

     for (auto i = 0; i < 10; ++i)
         arr.push_back([=]() { cout << i << " "; });

     for (auto f : arr)
         f();
 }
 ```
 Prints: 0 1 2 3 4 5 6 7 8 9

 One stupid solution is to replace `0 .. 10` with staticIota!(0, 
 10), which would unroll the loop at CT, but I want something 
 more general that would me allow me to capture the values of a 
 range while iterating over it at run-time.

I think these two links, more or less, answer my question:
http://stackoverflow.com/questions/29759419/closures-in-loops-capturing-by-reference
https://issues.dlang.org/show_bug.cgi?id=2043

Basile B. <b2.temp gmx.com> writes:

On Wednesday, 3 February 2016 at 18:09:52 UTC, ZombineDev wrote:
 I think these two links, more or less, answer my question:
 http://stackoverflow.com/questions/29759419/closures-in-loops-capturing-by-reference
 https://issues.dlang.org/show_bug.cgi?id=2043

Another approach:

import std.range, std.array, std.stdio;

struct InputRangeHook(T, alias Fun)
if (isInputRange!T)
{
     private T _t;
     this(T t)
     {
         _t = t;
     }
     void popFront()
     {
         Fun(front());
         _t.popFront;
     }
     bool empty()
     {
         return _t.empty();
     }
     auto front()
     {
         return _t.front;
     }
}

void main()
{
     foreach(i; InputRangeHook!(int[],(a) {write(a," 
");})(iota(0,10).array)){}
}

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 02/03/2016 10:09 AM, ZombineDev wrote:

 I think these two links, more or less, answer my question:
 

http://stackoverflow.com/questions/29759419/closures-in-loops-ca
turing-by-reference 

 https://issues.dlang.org/show_bug.cgi?id=2043

I find it more readable to give a name like makeClosure():

     foreach (i; 0 .. 10) {
         auto makeClosure = (int a) {
             return { write(a, " "); };
         };

         arr ~= makeClosure(i);
     }

Of course, makeClosure() can be moved out of the loop if needed.

Ali