Does cheetah look at superclasses of placeholder objects?

Howdy,

I've been using Cheetah for a few weeks and am pretty happy with it (I have been 
and still am a Velocity user too, so very familiar).  However, I'm running into 
a problem trying to invoke a method off a placeholder that makes me wonder if 
Cheetah is able to understand the placeholder objects might have superclasses 
and is able find methods in them.

NOTE: To be clear, I am NOT subclassing the cheetah Template class.  This is 
regarding an object that is added to my path which has a super class.

What is happening is that when I attempt to iterate over a list of objects, the 
individual objects appear to be complete (they are not None and a $type($xxx) 
returns the correct/expected type).  But any attempt to invoke a method on the 
placeholder that would in fact be a method in the placeholder objects super 
class fail with a

-------------------
   File "/usr/lib/python2.6/socket.py", line 292, in write
     data = str(data) # XXX Should really reject non-string non-buffers
   File "/usr/local/lib/python2.6/dist-packages/Cheetah/Template.py", line 997, 
in __str__
     rc = getattr(self, mainMethName)()
   File 
"_home_gerry_Dropbox_develop_shiftBrite_pyDriver_www_templates_editScript_tmpl.py", 
line 160, in respond
TypeError: 'NoneType' object is not callable
------------------

The fragment of the template file that is causing this is:
---------------------
#for $anEffect in $handler.getEffectList():
   $anEffect.getName()
#end for
---------------------

I can confirm, via debugging and copious print statements, that the object 
represented by $handler is returning a series of objects via the getEffectList() 
method.

Each "effect" instance can be a different class instance, but all the class 
instances have a common (and single) superclass that contains the getName() 
method.  For example, there could be a class of "effects.effects.ColorWasher", 
"effects.effects.ColorPulser" and "effects.effects.TwinkleColor".  All classes 
have the same base class of "BaseEffect" (which defined getName() and is not 
overridden by the sub-classes).

If I fire up the python shell and run all the same code by hand, the 
getEffectList() call correctly returns a list of effects instances which work 
fine (I can call the getName() and other methods no problem).  This code has 
been working for a long time, so I'm pretty confident of it.  I install the 
$handler value directly, so there are no intermediate classes that could 
hide/mask things.

The odd thing, to me, is that if I do
#for $anEffect in $handler.getEffectList():
   $type($anEffect)
#end for

I get an expected list of different class names, so it must see part of this, 
but an attempt to invoke any method (even methods I know do NOT exist -- just 
testing), gives the NoneType.  Doing a $dir($anEffect) shows all methods, 
including the getName() method, fine, so it's there in some way.

I have a ton of other placeholder activity including calls for other 
classes/lists of instances in the same template that work fine.

So, hoping I've provided enough to at least start the dialog, I'm wondering if:
1) Could there be issues because the method I'm trying to invoke belongs to a 
superclass of the instance that is being used?

2) Could there be an issue with packages/modules/importing that has to be 
resolved (i.e. while the class is intact, Cheetah can't parse the info/find 
things because the classes are from a different package/module)?

3) If none of the above, any suggestions on how to further track this down?

I really appreciate it.  I've spend nearly 2 days testing and trying different 
approaches and other than now being sure the underlying code (the handler, 
effects list manage and effects) are working reliably.

Much Thanks in advance!

Gerry
-- 
Gerry Duprey
Ann Arbor, MI 48103
http://www.cdp1802.org

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