[Web-SIG] WSGI and start_response

[P.J. Eby]

At 04:08 PM 4/8/2010 +0200, Manlio Perillo wrote:
>Hi.
>
>Some time ago I objected the decision to remove start_response function
>from next version WSGI, using as rationale the fact that without
>start_callable, asynchronous extension are impossible to support.
>
>Now I have found that removing start_response will also make impossible
>to support coroutines (or, at least, some coroutines usage).
>
>Here is an example (this is the same example I posted few days ago):
>http://paste.pocoo.org/show/199202/
>
>Forgetting about the write callable, the problem is that the application
>starts to yield data when tmpl.render_unicode function is called.
>
>Please note that this has *nothing* to do with asynchronus applications.
>The code should work with *all* WSGI implementations.
>
>
>In the pasted example, the Mako render_unicode function is "turned" into
>a generator, with a simple function that allows to flush the current buffer.
>
>
>Can someone else confirm that this code is impossible to support in WSGI
>2.0?

I don't understand why it's a problem.  See my previous post here:

http://mail.python.org/pipermail/web-sig/2009-September/003986.html

for a sketch of a WSGI 1-to-2 converter.  It takes a WSGI 1 
application callable as the input, and returns a WSGI 2 function.