On Mon, Sep 3, 2012 at 6:46 AM, Hartmut Kaiser <hartmut.kaiser@gmail.com> wrote:
Hi all,
The review of Oliver Kowalke's Boost.Coroutine library starts today, September 3rd 2012, and will end on September 12th. I really hope to see your vote and your participation in the discussions on the Boost mailing lists!
Hi Oliver, I'm new to this list but because I wanted a coroutine library for a long time, I want to participate in this review. I'm also very impressed by Boost.Context and glad that it stands as a standalone and not in the detail namespace of this coroutine library. I have a few questions, though. Starting with generator class (easiest): 1. What is the rationale for having the generator-function's return statement be used to return the last generated value or forcing the use of yield_break (which uses exceptions that can be slow). My only experience with generators/coroutines has been in Python which might have biased my view but I think having the generator-function return void would be more natural (and would eliminate the need for yield_break). For example, if I wanted to generate a sequence of evens, I could write: typedef boost::coro::generator< int > gen_t; gen_t evens(int cnt) { return [=](gen_t::self_t& self) { for( int i = 0; i < cnt; i++ ) self.yield(i*2); }; } 2. Considering that generators are used to produce a sequence of values, would it make sense to support range based for loop? While playing with the library, I defined a (hacky) iterator together with begin/end functions that made it possible to: for( int x: evens(10) ) std::cout << x << ' '; I found such usage very natural and wanted to find out if you considered adding such support? This should also make it possible to turn the generators into Boost.Range ranges. 3. Regarding both generator and coroutine classes. Their nested self_t class should perhaps be called caller_t as it encapsulates the caller's context and allows yielding the value _to_ the caller. It might then be possible to overload operator()(...): void gen_evens(gen_t::caller_t& caller) { for( int i = 0; i < 10; i++ ) caller(i*2); } This will achieve a nice symmetry with code that is sending values to the coroutines with the use of operator(). Regards, -Eugene