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Subject: [boost] [Review.Coroutine] Lifetime of coroutine parameters
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-09-10 17:28:06


I have some concerns about the lifetime of the coroutine parameters.

Surprisingly (well not really), the following example doesn't fails at
*1*. This is because the coroutine have access to its coroutine
parameters *2*, which has a sens only for the first time the coroutine
is called. Once the first call to yield return, the memory these
parameter *3* can point to trash, as the example shows.

typedef int TT;
typedef boost::coro::coroutine< void(TT&) > coro_TT;

void lifetime( coro_TT::self_t & self, TT& i ) // *2*
     TT& j = self.yield();
     std::cout << i << j << std::endl;

     i=2; // *3* UNSAFE access to i
void test_lifetime()
     coro_TT c( boost::bind( lifetime, _1, _2) );
         int k = 0;
         c( k );
         BOOST_CHECK(k = 1);

         int k = 0;
         int i = 0;
         c( i );
         BOOST_CHECK(k = 2); // *1*
         std::cout << i << k << std::endl;

This could hide errors that are difficult to catch. In addition to merit
to be mentioned in the documentation as a limitation of the current
library interface I really think that it merits to see if this can be


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