Allow req.add_handler()/req.register_*_filter() to take module/function for handler.

• Key: MODPYTHON-164
• Type: New Feature
• Status: Closed
• Resolution: Fixed
• Priority: Major
• Assignee: Graham Dumpleton
• Reporter: Graham Dumpleton
• Component/s: core
• Fix Version/s: 3.3.1

Description

Currently, the:

  req.add_handler(phase, handler, dir)
  req.register_input_filter(filter_name, filter, dir)
  req.register_output_filter(filter_name, filter, dir)

functions require the handler/filter to be a string. This string identifies the module that should be imported and which contains the necessary function, plus optionally, an alternate named function to the default for the phase or filter type. For example:

  req.add_handler("PythonHandler", "mymodule::myhandler")

It would be simpler if the handler/filter argument could be overloaded and instead supplied an actual module reference or callable object reference. For example:

  import mymodule

  def myhandler(req):
    ...

  def fixuphandler(req):
    req.add_handler("PythonHandler", mymodule)
    req.add_handler("PythonHandler", mymodule.myhandler)
    req.add_handler("PythonHandler", myhandler)
    return apache.OK

This would be easier than having to construct a string module/function reference when you have direct access to the handler function.

In the main the "dir" argument would be irrelevant. The only circumstance where it would matter is where PythonInterpPerDirective was used as it could be used to control the interpreter the code executed within. If not supplied, it could be argued that the directory where the supplied module/function is defined in should be used as "dir".

Comments

[Graham Dumpleton]

Change made, but require argument to functions be the actual callable object, no module reference allowed as suggested originally. Thus can write:

from mod_python import apache

def uppercase(filter):
    s = filter.read()
    while s:
        filter.write(s.upper())
        s = filter.read()
    if s is None:
        filter.close()

def handler(req):
    req.content_type = 'text/plain'
    req.write('handler')
    return apache.OK

def fixuphandler(req):
    req.handler = 'mod_python'
    req.register_output_filter("UPPERCASE", uppercase)
    req.add_output_filter("UPPERCASE")
    req.add_handler('PythonHandler', handler)
    return apache.OK

where Apache configuration just defines the fixup handler. For example:

PythonFixupHandler handlers

The speed increase is significant, as it avoids having to perform additional module lookups when string reference used.

This whole feature is very promising, as it would allow quite powerful dispatch mechanisms to be implemented where the decisions are made in the fixup handler phase rather than the response handler itself. All in all, provides more flexibility by doing it this way.