Re: So, what the heck is a continuation anyway?

[Paul Prescod <address@hidden>]

Dan Sugalski wrote:
> 
>...
> 
> Are there general rules as to where you're allowed to return to? I presume
> picking PC addresses out of the air's considered bad form.

In Scheme, you generate the "PC address" by saying
"call-with-current-continuation" (shortcut: call-cc).  It calls a
function, passing the current continuation as an argument. The
continuation object looks like a function (of course, in scheme, it
would look like a function). In Stackless Python it looks like an object
with a .call method. If you aren't comfortable with Scheme, consider
playing with them in Stackless Python.

http://www.ps.uni-sb.de/~duchier/python/continuations.html

Continuations are not something you would expect many programmers to
use. IMO, most programmers should work with pre-defined control
structures, not invent their own! Exception handling, co-operative
microthreads, coroutines and generators are all control flow structures
that can be implemented on top of continuations.

 Paul Prescod