[Web-SIG] Standardising containment.
Phillip J. Eby
pje at telecommunity.com
Mon Sep 6 16:11:02 CEST 2004
At 01:46 PM 9/6/04 +0100, Alan Kennedy wrote:
> >>1. Temporary storage/scratch directory.
>On thinking further about the temp directory issue, I see now that it is
>but one example of a class of problems relating to accessing physical
>resources on the local machine.
>The other main one that springs to mind is how WSGI applications discover
>the file-system path name that corresponds to an URI.
*boggle* Why do you think that URIs have anything to do with file
paths? In the general case, they are entirely unrelated.
>Therefore I propose that WSGI somehow attempt to standardise access to
>local resources on the disk. This could be done, perhaps, by providing a
>function which resolves a logical URI to a physical resource. J2EE has
>just such a function (surprise ;-), called ServletContext.getRealPath(),
>which returns a file-system path name which is relative to the
>CONTEXT_PATH mentioned above.
>Without WSGI providing such local mapping functions, I don't see how WSGI
>applications/middleware can map URIs to files, without undertaking
>platform specific tricks.
Well-written Python applications make this sort of thing part of their
configuration today already, because in the general case (e.g. mod_rewrite)
this stuff just plain isn't guessable.
Also, if you need access to local resources, relative to some Python
module, just grab the '__file__' attribute/variable of that module, and
then use 'os.path' functions to portably manipulate it. E.g.:
my_dir = os.path.dirname(__file__)
target = os.path.join(os.path.join(my_dir,"images"),"stars.jpg")
This is simple and portable. If you need something more complex, you
should probably have configuration specific to the application that spells
out what it needs to know.
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