[IronPython] .NET attributes for methods

Lukas Cenovsky cenovsky at bakalari.cz
Fri Nov 13 05:41:38 PST 2009


This looks very promising but I cannot make it work. I have changed 
product.py in DevHawk's example to:

#from clrtypeold import ClrMetaclass
import clrtype

class Product(object):
  #__metaclass__ = ClrMetaclass
  __metaclass__ = clrtype.ClrClass
  _clrnamespace = "DevHawk.IronPython.ClrTypeSeries"
  #_clrproperties = {
    #"name":str,
    #"cost":float,
    #"quantity":int,
    #}
    
  def __init__(self, name, cost, quantity):
    self.name = name
    self.cost = cost
    self.quantity = quantity
    
  def calc_total(self):
    return self.cost * self.quantity

  @property
  @clrtype.accepts()
  @clrtype.returns(str)
  def name(self):
      return self._name

  @name.setter
  @clrtype.accepts(str)
  @clrtype.returns()
  def name(self, value):
      self._name = value


When I run it I don't see any items in the listbox. When I check the 
name, it is a property:

py> a.root.listbox1.Items[0]

=> <Product object at 0x000000000000002B>

py> a.root.listbox1.Items[0].GetType().GetProperties()

=> Array[PropertyInfo]((<System.Reflection.RuntimePropertyInfo object at 0x000000000000002C [System.String name]>))

Whe I used the old clrtype with _clrproperties = {'name': str, ...}, it 
worked.

--
-- Lukáš


Shri Borde wrote:
>
> Here is an updated version of clrtype.py that uses @property + 
> @clrtype.accepts/@clrtype.returns to indicate a CLR property, instead 
> of using "_clrproperties". I think its more Pythonic in general, but 
> also you should be able to modify @notify_property to work with it.
>
>  
>
> Note that notify_property won't just work. You will have to change it 
> to propagate the func_name, arg_types, and return_type properties from 
> the old getter/setter function objects to the new getter/setter 
> function objects since these values are used by clrtype to generate 
> the CLR members. Something like this:
>
>  
>
> class notify_property(property):
>
>  
>
>     def propagate_attributes(old_function, new_function):
>
>         new_function.func_name = old_function.func_name
>
>         new_function.arg_types = old_function.arg_types
>
>         new_function.return_type = old_function.return_type
>
>  
>
>     def __init__(self, getter):
>
>         def newgetter(slf):
>
>             try:
>
>                 return getter(slf)
>
>             except AttributeError:
>
>                 return None
>
>         propagate_attributes(getter, newgetter)
>
>         super(notify_property, self).__init__(newgetter)
>
>  
>
>     def setter(self, setter):
>
>         def newsetter(slf, newvalue):
>
>             oldvalue = self.fget(slf)
>
>             if oldvalue != newvalue:
>
>                 setter(slf, newvalue)
>
>                 slf.OnPropertyChanged(setter.__name__)
>
>         propagate_attributes(setter, newsetter)
>
>         return property(
>
>             fget=self.fget,
>
>             fset=newsetter,
>
>             fdel=self.fdel,
>
>             doc=self.__doc__)
>
>  
>
> *From:* Lukas Cenovsky [mailto:cenovsky at bakalari.cz]
> *Sent:* Thursday, November 12, 2009 11:01 AM
> *To:* Shri Borde
> *Subject:* Re: [IronPython] .NET attributes for methods
>
>  
>
> Shri Borde wrote:
>
> So the new clrtype.py still works - cool!
>
> Yep ;-)
>
>  I am not an expert on data binding, so I don't have any suggestions. 
> Why do you say that the decorator approach will not work with 
> Silverlight? Does @notifiy_property from 
> http://gui-at.blogspot.com/2009/11/inotifypropertychanged-in-ironpython.html 
> use any feature not available in Silverlight?
>
> It does not (as far as I know because it is pure IronPython). But 
> @notify_property does not work with clrtypes:
>
> class ViewModel(NotifyPropertyChangedBase):
>     __metaclass__ = clrtype.ClrMetaclass
>     _clrnamespace = "Cenda.ViewModel"
>     _clrproperties = {'size': str}
>     
>     def __init__(self):
>         super(ViewModel, self).__init__()
>         # must be string to two-way binding work correctly
>         self.size = '10'
>  
>     @notify_property
>     def size(self):
>         return self._size
>  
>     @size.setter
>     def size(self, value):
>         self._size = value
>         print 'Size changed to %r' % self.size
>  
>
>
> When I run this code, the size is still clr property and Python getter 
> and setter are not run.
>
> So basically I need to override/enhance clr getter and setter created 
> by clrtype._clrproperties.
>
> --
> -- Lukáš
>
>
>  
>
> *From:* Lukas Cenovsky [mailto:cenovsky at bakalari.cz]
> *Sent:* Thursday, November 12, 2009 8:09 AM
> *To:* Shri Borde
> *Subject:* Re: [IronPython] .NET attributes for methods
>
>  
>
> Thanks, that works!
>
> What do you think would be the best approach to create notifiable 
> properties for Silverlight? I did it for WPF (via decorators: 
> http://gui-at.blogspot.com/2009/11/inotifypropertychanged-in-ironpython.html) 
> but it seems to me it won't be possible to do it similarly for 
> Silverlight...
>
> --
> -- Lukáš
>
> Shri Borde wrote:
>
> Can you use "_clrproperties" instead of "_clrfields"? DevHawk's same 
> created a field and a property even when you just used "_clrfields". I 
> don't do that anymore. So you will need to use "_clrproperties" to get 
> properties, which SL must use for data binding.
>
>  
>
> *From:* users-bounces at lists.ironpython.com 
> <mailto:users-bounces at lists.ironpython.com> 
> [mailto:users-bounces at lists.ironpython.com] *On Behalf Of *Lukas Cenovsky
> *Sent:* Wednesday, November 11, 2009 2:37 AM
> *To:* Discussion of IronPython
> *Subject:* Re: [IronPython] .NET attributes for methods
>
>  
>
> I did change __metaclass__ to ClrMetaclass. See the attached source I 
> use for testing - the only difference is to comment/uncomment 
> appropriate part in product.py.
>
> The outputs look the same, there are no visible exceptions:
>
> DevHawk:
>
> py> a.root.FindName('listbox1').ItemsSource[0].GetType().GetFields()
> => Array[FieldInfo]((<System.Reflection.RtFieldInfo object at 0x000000000000002B [Double cost]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002C [Int32 quantity]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002D [System.String name]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002E [IronPython.Runtime.Types.PythonType .class]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002F [IronPython.Runtime.PythonDictionary .dict]>,
> <System.Reflection.RtFieldInfo object at 0x0000000000000030 [System.Object[] .slots_and_weakref]>))
>
>
> Shri:
>
> py> a.root.FindName('listbox1').ItemsSource[0].GetType().GetFields()
> => Array[FieldInfo]((<System.Reflection.RtFieldInfo object at 0x000000000000002B [Double cost]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002C [Int32 quantity]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002D [System.String name]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002E [IronPython.Runtime.Types.PythonType .class]>,
> <System.Reflection.RtFieldInfo object at 0x000000000000002F [IronPython.Runtime.PythonDictionary .dict]>,
> <System.Reflection.RtFieldInfo object at 0x0000000000000030 [System.Object[] .slots_and_weakref]>))
>
>  
>
> --
> -- Lukáš
>
>
> Shri Borde wrote:
>
> Note that you will have to set __metaclass__ to ClrMetaclass, not 
> ClrTypeMetaclass as in DevHawk's sample. I had changed the name of the 
> type. The old name will cause a NameError, but maybe SL is hiding 
> exceptions. Can you do "o.GetType().GetFields()" and display that on 
> the page to inspect the object and also make sure that no exceptions 
> were thrown?
>
>  
>
> *From:* users-bounces at lists.ironpython.com 
> <mailto:users-bounces at lists.ironpython.com> 
> [mailto:users-bounces at lists.ironpython.com] *On Behalf Of *Lukas Cenovsky
> *Sent:* Tuesday, November 10, 2009 2:59 PM
> *To:* Discussion of IronPython
> *Subject:* Re: [IronPython] .NET attributes for methods
>
>  
>
> I have just found that the Silverlight binding does not work with this 
> version of clrtype and/or IronPython 2.6RC2.
> I used DevHawk demo [1] and after I added reference to 
> Microsoft.Dynamic in clrtypemetaclass.py it worked flawlessly. But 
> when I switch to your version, no items show in the listbox.
>
> By the way - I have seen a commit message you have added support for 
> interfaces - nice! ;-)
>
> --
> -- Lukáš
>
> [1] 
> http://cid-0d9bc809858885a4.skydrive.live.com/self.aspx/DevHawk%20Content/IronPython%20Stuff/^_^_clrtype^_^_/SL%20databinding%20demo.zip 
> <http://cid-0d9bc809858885a4.skydrive.live.com/self.aspx/DevHawk%20Content/IronPython%20Stuff/%5E_%5E_clrtype%5E_%5E_/SL%20databinding%20demo.zip>
>
>  
>
>  
>
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>
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