Re: [Python-Dev] Coroutines, generators, function calling
so the new syntax would not be useful, unless it was something that provided access to the index item as a variable, like: yield foo(i) for i in x which barely saves you anything (a colon, a newline, and an indent). Not even that, because you can omit the newline and indent: for i in x: yield foo(i) There's a bigger difference between for i in x: yield i and yield from x Moreover, I can imagine optimization opportunities for yield from that would not make sense in the context of comprehensions. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Coroutines, generators, function calling
Andrew Koenig wrote: Sure, that would work. Or even this, if the scheduler would automatically recognize generator objects being yielded and so would run the the nested coroutine until finish: This idea has been discussed before. I think the problem with recognizing generators as the subject of yield statements is that then you can't yield a generator even if you want to. The best syntax I can think of without adding a new keyword looks like this: yield from x which would be equivalent to for i in x: yield i My eyes really like the syntax, but I wonder about it's usefulness. In rdflib, particularly here: http://svn.rdflib.net/trunk/rdflib/backends/IOMemory.py We yield values from inside for loops all over the place, but the yielded value is very rarely just the index value (only 1 of 14 yields) , but something calculated from the index value, so the new syntax would not be useful, unless it was something that provided access to the index item as a variable, like: yield foo(i) for i in x which barely saves you anything (a colon, a newline, and an indent). (hey wait, isn't that a generator comprehension? Haven't really encountered those yet). Of course rdflib could be the minority case and most folks who yield in loops are yielding only the index value directly. off to read the generator comprehension docs... -Michel ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] Coroutines, generators, function calling
There's one thing about coroutines using python generators that is still troubling, and I was wondering if anyone sees any potencial solution at language level... Suppose you have a complex coroutine (this is just an example, not so complex, but you get the idea, I hope): def show_message(msg): win = create_window(msg) # slide down for y in xrange(10): win.move(0, y*20) yield Timeout(0.1) # timeout yield Timeout(3) # slide up for y in xrange(10, 0, -1): win.move(0, y*20) yield Timeout(0.1) win.destroy() Suppose now I want to move the window animation to a function, to factorize the code: def animate(win, steps): for y in steps: win.move(0, y*20) yield Timeout(0.1) def show_message(msg): win = create_window(msg) animate(win, xrange(10)) # slide down yield Timeout(3) animate(win, xrange(10, 0, -1)) # slide up win.destroy() This obviously doesn't work, because calling animate() produces another generator, instead of calling the function. In coroutines context, it's like it produces another coroutine, while all I wanted was to call a function. I don't suppose there could be a way to make the yield inside the subfunction have the same effect as if it was inside the function that called it? Perhaps some special notation, either at function calling or at function definition? -- Gustavo J. A. M. Carneiro [EMAIL PROTECTED] [EMAIL PROTECTED] The universe is always one step beyond logic. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Coroutines, generators, function calling
Gustavo J. A. M. Carneiro wrote: I don't suppose there could be a way to make the yield inside the subfunction have the same effect as if it was inside the function that called it? Perhaps some special notation, either at function calling or at function definition? You mean like a for loop? ;) def show_message(msg): win = create_window(msg) for step in animate(win, xrange(10)): # slide down yield step yield Timeout(3) for step in animate(win, xrange(10, 0, -1)): # slide up yield step win.destroy() Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.blogspot.com ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Coroutines, generators, function calling
On Tue, 2005-10-18 at 09:07 -0400, Jim Jewett wrote: Suppose now I want to move the window animation to a function, to factorize the code: def animate(win, steps): for y in steps: win.move(0, y*20) yield Timeout(0.1) def show_message(msg): win = create_window(msg) animate(win, xrange(10)) # slide down yield Timeout(3) animate(win, xrange(10, 0, -1)) # slide up win.destroy() This obviously doesn't work, because calling animate() produces another generator, instead of calling the function. In coroutines context, it's like it produces another coroutine, while all I wanted was to call a function. I don't suppose there could be a way to make the yield inside the subfunction have the same effect as if it was inside the function that called it? Perhaps some special notation, either at function calling or at function definition? - I may be missing something, but to me the answer looks like: def show_message(msg): win = create_window(msg) for v in animate(win, xrange(10)): # slide down yield v yield Timeout(3) for v in animate(win, xrange(10, 0, -1)): # slide up yield v win.destroy() Sure, that would work. Or even this, if the scheduler would automatically recognize generator objects being yielded and so would run the the nested coroutine until finish: def show_message(msg): win = create_window(msg) yield animate(win, xrange(10)) # slide down yield Timeout(3) yield animate(win, xrange(10, 0, -1)) # slide up win.destroy() Sure, it could work, but still... I wish for something that would avoid creating a nested coroutine. Maybe I'm asking for too much, I don't know. Just trying to get some feedback... Regards. -- Gustavo J. A. M. Carneiro [EMAIL PROTECTED] [EMAIL PROTECTED] The universe is always one step beyond logic. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Coroutines, generators, function calling
Sure, that would work. Or even this, if the scheduler would automatically recognize generator objects being yielded and so would run the the nested coroutine until finish: This idea has been discussed before. I think the problem with recognizing generators as the subject of yield statements is that then you can't yield a generator even if you want to. The best syntax I can think of without adding a new keyword looks like this: yield from x which would be equivalent to for i in x: yield i Note that this equivalence would imply that x can be any iterable, not just a generator. For example: yield from ['Hello', 'world'] would be equivalent to yield 'Hello' yield 'world' ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Coroutines, generators, function calling
At 12:01 PM 10/18/2005 +0100, Gustavo J. A. M. Carneiro wrote: def show_message(msg): win = create_window(msg) animate(win, xrange(10)) # slide down yield Timeout(3) animate(win, xrange(10, 0, -1)) # slide up win.destroy() This obviously doesn't work, because calling animate() produces another generator, instead of calling the function. In coroutines context, it's like it produces another coroutine, while all I wanted was to call a function. Just 'yield animate(win, xrange(10))' and have the trampoline recognize generators. See the PEP 342 trampoline example, which does this. When the animate() is exhausted, it'll resume the calling function. I don't suppose there could be a way to make the yield inside the subfunction have the same effect as if it was inside the function that called it? Perhaps some special notation, either at function calling or at function definition? Yes, it's 'yield' at the function calling. :) ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
