I didn't understand it too much, but maybe it is worth to check it ? Cheers, Mariano ---------- Forwarded message ---------- From: Stephen Pair <stephen@pairhome.net> Date: Mon, Dec 14, 2009 at 2:22 AM Subject: [squeak-dev] [ANN] CoroutineReadStream (again) To: The general-purpose Squeak developers list < squeak-dev@lists.squeakfoundation.org> This version fixes a bug in #close that causes the coroutine to not get unwound when the stream is closed. Also, it now uses the stream itself as a marker instead of a special string (a suggestion from Eliot). I've also created unit tests (which is how I caught the problem with close). Below is the class comment: ----- I enable the use of a ReadStream interface in cases where enumeration protocol is available, but no read stream interface is available. For example, I can adapt any object that supports #do: for enumeration: CoroutineReadStream on: #(1 2 3) iterator: #do: The implementation makes use of coroutines to avoid the need to create and schedule a separate Process. Sending #close will abandon the coroutine and unwind all contexts in the coroutine. The coroutine is not invoked until the first request for an object. The iterator is finished when there is an attempt to read past the end (via #next or #peek), or when there is an #atEnd test after the last object was retrieved. A CoroutineReadSteam is not particularly efficient due to its use of thisContext and how stacks are optimized in most Smalltalk implementations. Instance Variables: nextValue <Object | noObjectMarker> Holds the next value to be answered when #next is called (needed to support #peek and #atEnd)...if it holds the noObjectMarker, it inticates that the coroutine needs to be invoked to get the next object. suspendedContext <ContextPart> This is either the context of the iterating stack (when not actively retrieving the next object for a client) or the stack of the user of the stream (when of retrieving the next object) homeContext <MethodContext> Holds the context of #initializeForBlock: called during instantiation and is used to ensure that exception propagation and handling works as one would expect. Copyright (c) 2009 Stephen Pair Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. - Stephen