[IronPython] Metaclass Error

[Nathan R. Ernst]

With the following (contrived) metaclass sample, I get a NotImplementedError
on the indicated line.  It appears to be due to IPythonContainer interface
members being unimplemented in IronPython.Runtime.ReflectedType.  I've
attached the .Net stack separately as it was a little ugly.

 

#######Begin Code Block 1 #######

#!/usr/bin/env python

 

class DataType(type):

      

      def __init__(cls, name, bases, dct):

            dct = dict([(k, cls.make_prop(cls, k, v)) for k, v in
dct.iteritems()])

            type.__init__(cls, name, bases, dct)

      

      def make_prop(cls, name, type, read_only=False): 

            prop_name = '_%s__%s' % (cls.__name__, name)

            

            def setter(self, __x):

                  setattr(self, prop_name, type(__x))

            

            def getter(self):

                  return getattr(self, prop_name)

            

            if read_only:                             ## Error occurs here.

                  return property(getter)

            else:

                  return property(getter, setter)

 

class Test(object):

      __metaclass__ = DataType

      foo = str

      bar = int

 

t = Test()

t.foo = 'Hello World'

t.bar = 42

 

print '%s: %d' % (t.foo, t.bar)

 

#######End Code Block 1 #######

 

 

IronPython stack:

 

  File .\metatest.py, line 23, in Initialize

  File .\metatest.py, line 6, in __init__

  File .\metatest.py, line 18, in make_prop

NotImplementedError: The method or operation is not implemented.

 

 

CPython output:

Hello World: 42


if I comment out the "if read_only.else" lines yielding the second code
block, the code works.

 

#######Begin Code Block 2 #######

#!/usr/bin/env python

 

class DataType(type):

      

      def __init__(cls, name, bases, dct):

            dct = dict([(k, cls.make_prop(cls, k, v)) for k, v in
dct.iteritems()])

            type.__init__(cls, name, bases, dct)

      

      def make_prop(cls, name, type, read_only=False):

            prop_name = '_%s__%s' % (cls.__name__, name)

            

            def setter(self, __x):

                  setattr(self, prop_name, type(__x))

            

            def getter(self):

                  return getattr(self, prop_name)

            

            return property(getter, setter)

 

class Test(object):

      __metaclass__ = DataType

      foo = str

      bar = int

 

t = Test()

t.foo = 'Hello World'

t.bar = 42

 

print '%s: %d' % (t.foo, t.bar)

 

#######End Code Block 2#######

 

Output:

Hello World: 42

 

 

I've not yet had a chance to take a crack at a patch, but I wanted to bring
this up as soon as possible.

 

Thanks, as always, for all your hard work, guys.

 

-Nathan Ernst

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