[Web-SIG] Future of WSGI

[Tres Seaver]

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Aaron Watters wrote:
> 
> --- On Wed, 11/25/09, Chris Dent <chris.dent at gmail.com> wrote:
> 
>> From: Chris Dent <chris.dent at gmail.com>
>> I can (barely) relate to some of the complaints that
>> start_response is a pain in the ass, but environ, to me, is
>> not broken.
> 
> I agree.  It maps nicely onto the underlying protocol
> and WSGI is supposed to be low level right?
> 
> The biggest problem with start_response is that after
> you evaluate
> 
>     iterable = application(env, start_response)
> 
> Sometimes the start_response has been called and sometimes
> it hasn't, and this can break middlewares when they haven't
> been tested both ways (repose.who for example seems to
> assume it has been called).

Since version 1.0.13 (2009-04-24), repoze.who's middleware is very
careful to dance around the fact that an application is not required to
have called 'start_response' on return, but *must* call it before
returning the first chunk from its iterator.  That bit of flexibility in
 PEP 333 is likely there to support *some* use case, but it makes
'start_response' a *big* pain to work with in middleware which needs to
to "egress" processing of headers.


Tres.
- --
===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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