Webware for Python

On April 26, 2002 06:06 pm, Terrel Shumway wrote:
> http://webware.colorstudy.net/twiki/bin/view/Webware/UriMapping is for =
a
> concrete implementation that can go into Webware RSN that can replace
> the current filesystem-centric mapping strategy.

Tangent 1
-----------

This URI topic is somewhat related to how contexts/packages are loaded in=
to=20
WebKit.  The current implementation of ServletFactory relies on the 'imp'=
=20
module and thus can't take any advantage of custom import hooks.  As a=20
result, you have to create a new servlet factory for .tmpl files, .psp fi=
les,=20
etc., in addition to any import hooks you've written. =20

The code in ServletFactory.importAsPackage() and=20
ServletFactory._importModuleFromDirectory could be refactored to allow it=
 to=20
work with import hooks and remove the need for a separate ServletFactory =
for=20
each extension.  It should be possible to use a single ServletFactory for=
=20
=2Epy, .psp, and .tmpl servlets once the refactoring has been done and an=
=20
import hook has been written for .psp files. =20

Tangent 2
-----------

The current implementation of psp doesn't allow one psp servlet to seemle=
ssly=20
inherit from another psp servlet.  An import hook would make this possibl=
e.=20
Ditto for .tmpl files.  I've written an import hook for .tmpl files (usin=
g=20
Gordon McMillan's ui.py rather than ihooks or imputils, which are both ba=
dly=20
broken).  See ImportManager.py and ImportHooks.py in Cheetah's CVS.  It=20
should be fairly simple to extend this to work with PSP as well.  Anyone=20
interested?

Tavis

On Fri, 2002-04-26 at 18:56, Tavis Rudd wrote:
> On April 26, 2002 06:06 pm, Terrel Shumway wrote:
> > http://webware.colorstudy.net/twiki/bin/view/Webware/UriMapping is for a
> > concrete implementation that can go into Webware RSN that can replace
> > the current filesystem-centric mapping strategy.
> 
> Tangent 1
> -----------
> 
> This URI topic is somewhat related to how contexts/packages are loaded into 
> WebKit.  The current implementation of ServletFactory relies on the 'imp' 
> module and thus can't take any advantage of custom import hooks.  As a 
> result, you have to create a new servlet factory for .tmpl files, .psp files, 
> etc., in addition to any import hooks you've written. 
 
Yes, and you SHOULD have to create a new ServletFactory.  

  class ServletFactory(Object):
	"""ServletFactory is an abstract class that defines the protocol
        for all servlet factories.
        ..."""
 
PythonServletFactory is designed for creating Servlet instances from
Python modules. period.

  class PythonServletFactory(ServletFactory):
	'''
	This is the factory for ordinary, Python servlets whose
        extensions are empty or .py. The servlets are unique per 
        file since the file itself defines the servlet.
        '''

This doc string certainly does not apply to all useful servlets.



> The code in ServletFactory.importAsPackage() and 
> ServletFactory._importModuleFromDirectory could be refactored to allow it to 
> work with import hooks and remove the need for a separate ServletFactory for 
> each extension.  It should be possible to use a single ServletFactory for 
> .py, .psp, and .tmpl servlets once the refactoring has been done and an 
> import hook has been written for .psp files.  


An even better idea would be to factor out the import code (remove
importAsPackage entirely from the ServletFactory interface or move it
down into PythonServletFactory), separate it from imp (as you
suggested), and make it available as a Loader class, to which
PythonServletFactory and others could delegate as necessary.

Removing the need for separate ServletFactory for each extension would
defeat the primary purpose of its design.

On April 29, 2002 06:52 am, Terrel Shumway wrote:
> On Fri, 2002-04-26 at 18:56, Tavis Rudd wrote:
> > The code in ServletFactory.importAsPackage() and
> > ServletFactory._importModuleFromDirectory could be refactored to allo=
w it
> > to work with import hooks and remove the need for a separate
> > ServletFactory for each extension.  It should be possible to use a si=
ngle
> > ServletFactory for .py, .psp, and .tmpl servlets once the refactoring=
 has
> > been done and an import hook has been written for .psp files.
>
> An even better idea would be to factor out the import code (remove
> importAsPackage entirely from the ServletFactory interface or move it
> down into PythonServletFactory), separate it from imp (as you
> suggested), and make it available as a Loader class, to which
> PythonServletFactory and others could delegate as necessary.
>
> Removing the need for separate ServletFactory for each extension would
> defeat the primary purpose of its design.

I'm not suggesting one ServletFactory for all extensions; rather, allowin=
g=20
multiple extensions to be explicitly mapped to one type of ServletFactory=
 in=20
cases where it makes sense.=20

ServletFactories should map to how Python sees a file, not to its extensi=
on.=20
Once an import hook has been installed, .tmpl and .psp files ARE=20
PythonServlets.  Python treats them as such, so should WebKit. =20

It's not a huge issue, but why require more code when you can do the same=
 with=20
less?

Tavis