Comments on Thinking Asynchronously in C++: Secret sauce revealed

Perhaps user error, but in VC9 this sample seems t...

2010-01-28T14:46:05.008+11:00

Perhaps user error, but in VC9 this sample seems to build in Debug but not in Release. An attempt at a release build causes a link error for 'you_forgot_to_add_the_entry_label' despite the fact that the code builds and runs with a debug build.

You should explain how those macros work. There se...

2009-12-26T10:14:35.956+11:00

You should explain how those macros work. There seem to be many "tricks" that are useful but aren't required to make coroutines work.

For example, it *seems* to me that the for loop inside 'yield' is just a trick to execute something *after* the yield expression while not making yield use function syntax.

Similarly for you_forgot_to_add_the_entry_label. I suspect it would be easier to follow if you remove the "feature" of: giving a readable warning if you forget the entry label.

Maybe show it as a tutorial for creating such a macro. Start simple, then add the tricks one by one...

@chris I ran into the local class used as a templa...

2009-08-27T20:11:56.424+10:00

@chris I ran into the local class used as a template argument error today. Good call. I -was- using Visual Studio VC9, and now I'm using MinGW.

I will like C++0x lambdas when we get to that poin...

2009-08-23T19:21:23.191+10:00

I will like C++0x lambdas when we get to that point. Until then..

No the first argument is just the name of the local class. Second argument is the main class all the callbacks are inside, simply because 'this' pointer changes. Can't access variables outside the inner scopes, so boxing/unboxing named variable list. Really shotty, but it seems to work. It's like extremely verbose ActionScript/JavaScript function objects (usually used as callbacks).

@Daemn: Looks like you would like C++0x lambdas th...

2009-08-23T08:58:27.659+10:00

@Daemn: Looks like you would like C++0x lambdas then. However, I'm a little confused: don't your macros create local classes? What compiler are you using, because (pre-C++0x) you can't use local classes as template parameters.

BTW I'm still debugging that code, it's na...

2009-08-22T21:56:28.701+10:00

BTW I'm still debugging that code, it's nasty, but gets the point across.

That's interesting... I wanted easier program...

2009-08-22T21:55:01.483+10:00

That's interesting...

I wanted easier program flow usage, and didn't want to embed a scripting language (yet). So I wrapped it up in a macro ("CREATE_CALLBACK")..

http://pastebin.ca/1538834

Instead of deriving my class, Application::Main, from it, I pass it a an argument. Not really the same as a coroutine, but the point was the same ("the control flow is all in one place and easy to follow"). I find using Asio a lot easier this way. Any suggestions?

Thanks again for Asio!

That's correct. If you want your coroutine to ...

2009-08-12T08:15:23.234+10:00

That's correct. If you want your coroutine to have "local" variables, you should make them data members of the function object.

Question: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ voi...

2009-08-12T05:33:06.068+10:00

Question:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
void operator()(
error_code ec = error_code(),
size_t length = 0)
{
int a = 0;

reenter (this)
{
entry:
for (;;)
{
yield acceptor_.async_accept(
*socket_, *this);

a = 1;

while (!ec)
{
yield socket_->async_read_some(
buffer(*data_), *this);

// what is a here?
a = 1;

if (ec) break;

yield async_write(*socket_,
buffer(*data_, length), *this);

// what is a here?
a = 2;

}

socket_->close();
}
}
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I think "a" at question places will always be 0. Am I right?