Roxen & Pike List Archives

 >int sum;
 >for(int i=0;i<100;i++){
 >    Thread.Thread(lambda(){
 >        /* too much code here, and take a long time to run */
 >        write("%d\n",i);
 >        sum+=i;
 >        /* too much code here too*/
 >    });
 >}

So, the problem is that you're using variables you thought were local,
but they aren't?

 >My problem is not "how to write correct code" but "how to avoid mistake"

But I don't see how your proposal would solve that problem. 

All non-local variables would be thread-shared if you're using threads
anywhere in the environment. A lambda isn't special. I'm not sure
where you would want the warning - in the use of lambdas with
out-of-scope variables that are given as argument to Thread.Thread()?

Should this give a warning to? Where?

    int global_variable;
    function f=lambda() { global_variable++; }
    void myfunc() { Thread.Thread(f); }

this?

    function g() { global_variable++; };
    function f=g;
    void myfunc() { Thread.Thread(f); }

And locks really doesn't have anything to do with the problem of
variables changing value outside the thread:

   Thread.Mutex i_lock=Thread.Mutex();
   object key=i_lock()->lock;
   for(int i=0;i<100;i++){
       Thread.Thread(lambda(){
           object key=i_lock()->lock;
           ...i...
           destruct(key);
       })};
   destruct(key);

or even

   Thread.Mutex i_lock=Thread.Mutex();
   for (int i=0; i<100; )
   {
       Thread.Thread(lambda(){
           object key=i_lock()->lock;
           ...i...
           destruct(key);
       });
       object key=i_lock()->lock;
       i++;
       destruct(key);
   }

seems to solve the problem you mention.


Sorry if I'm confused...