[Zope] - Problem with ExternalMethod

[Jim Fulton]

A.M. Kuchling wrote:
> 
> I'm trying to figure out how to create a function that can be turned
> into an ExternalMethod.  The module name is AMK.Tester, and the
> function name is test1.
> 
>         The steps I followed were:
> 
> 1) Create an AMK/Extensions directory in the Products/ directory.
> 2) Create Tester.py in the AMK/Extensions directory, and put a test()
>    function in it.
> 3) Encrypt the .py file to produce a .pyp file with a little program.
> 4) Attempting to create the ExternalMethod object gets a traceback:
> 
> Traceback (innermost last):
>   File /home/opt/zope/lib/python/ZPublisher/Publish.py, line 861, in publish_module
>   File /home/opt/zope/lib/python/ZPublisher/Publish.py, line 583, in publish
>     (Info: /manage_addExternalMethod)
>   File /home/opt/zope/lib/python/Products/ExternalMethod/ExternalMethod.py, line 125, in manage_addExternalMethod
>     (Object: ApplicationDefaultPermissions)
>   File /home/opt/zope/lib/python/Products/ExternalMethod/ExternalMethod.py, line 167, in __init__
>     (Object: Item)
>   File /home/opt/zope/lib/python/Products/ExternalMethod/ExternalMethod.py, line 186, in manage_edit
>     (Object: Item)
>   File /home/opt/zope/lib/python/Products/ExternalMethod/ExternalMethod.py, line 206, in getFunction
>     (Object: Item)
>   File /home/opt/zope/lib/python/App/Extensions.py, line 104, in __cmp__
> AttributeError: 'None' object has no attribute 'co_argcount'
> 
> Looking at the code in ExternalMethod.py, the ExternalMethod class
> attribute func_code is set to None.  When .getFunction() is called,
> self.func_code is None, so the comparison in the following line fails:
>             if func_code != self.func_code: self.func_code=func_code
> 
> The FuncCode.__cmp__ method is:
>     def __cmp__(self,other):
>         return cmp((self.co_argcount, self.co_varnames),
>                    (other.co_argcount, other.co_varnames))
> 
> other is None, so the AttributeError results.  I don't see what the
> problem is, unless some external thing is expected to set the
> .func_code attribute.  Or are there more things that I need to define
> in my package directory?

The problem is that in Python 1.4, errors in cmp were ignored
and caused an effective enequality.  In Python 1.5 cmp is handled 
differently, which is a good thing, and I failed to test ExternalMethod
with it, which is a bad thing. :|

The next release will have following __cmp__ function, which seems to
solve the problem:

    def __cmp__(self,other):
        if other is None: return 1
        try: return cmp((self.co_argcount, self.co_varnames),
                        (other.co_argcount, other.co_varnames))
        except: return 1


--
Jim Fulton           mailto:jim@digicool.com
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