[Web-SIG] about Py[Type]_Check in a WSGI implementation

Manlio Perillo manlio_perillo at libero.it
Fri Oct 19 21:43:39 CEST 2007

Ian Bicking ha scritto:
> Manlio Perillo wrote:
>> The WSGI spec requires the response headers and sequence items to be, 
>> respectively, List of Tuples and Strings.
>> However only for the response headers it explicitly requires them to 
>> be a Python List, i.e type(response_headers) is ListType.
>> What about the other objects?
>> In the current implementation of WSGI for Nginx I always use 
>> Py[Type]_Check, and not Py[Type]_CheckExact.
> All of the types are required to be exactly as defined, not subclasses 
> or None.  But servers are not required to actually test this. 
> wsgiref.validate does test for exactly these types, but it's acceptable 
> for Nginx to just access the data without checking its exact type.

Ok, thanks.

However it is not a problem to use Py[Type]_Check instead of 
Py[Type]_CheckExact (and it should not be slower), so if the types are 
required to be exactly as defined I think it is better to do the exact 

In mod_wsgi for Nginx I'm doing a lot of checks (as an example I even 
check if the write callable is called from within application iterable)

Manlio Perillo

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