Hmm, the fact that we aren't picking up __radd__ properly looks like a bug,
which I'll go ahead and log on CodePlex. The good news is that there's a more
common usage pattern that works correctly.
The canonical way to do this is to define + and - as static (Shared in VB
speak) operator methods. These should automatically manifest themselves as
__add__, __radd__, __sub__, and __rsub__ in IronPython. Specifically, I
recommend trying something like this:
Public Structure NumericObject
...
' This method should become __add__
Public Shared Operator +(ByVal self As NumericObject, ByVal other As Object) _
...
End Operator
' This method should become __radd__
Public Shared Operator +(ByVal other As Object, ByVal self As NumericObject) _
Return self + other
End Operator
' Ditto with subtraction
...
End Structure
In addition, if you're only interested in adding/subtracting objects of the
same type, you need only define each operator once:
Public Structure NumericObject
...
' This method should become __add__ and __radd__
Public Shared Operator +(ByVal self As NumericObject, ByVal other As
NumericObject) _
...
End Operator
' Ditto with subtraction
...
End Structure
I've only tested this in C# against IPy 2.6, so please let me know how it turns
out. Good luck!
- David
From: [email protected]
[mailto:[email protected]] On Behalf Of Ricardo
Sent: Sunday, June 07, 2009 7:26 PM
To: [email protected]
Subject: [IronPython] Emulating numeric type in C# or VB.net , __radd__ is not
called
I testing IronPython 2.0 and trying to integrate with my VB.NET application.
I would like to create an object to emulate a numeric type implementing the
functions
__add__, __radd__ , __sub__ , __rsub__ , etc as explained in Python manual
http://www.python.org/doc/2.5.2/ref/numeric-types.html
I would like to create this emulated object inside my vb.net application and
import this object from a python code like the example below
#IronPython code
#Vb.NET object
from IronPytonTest import TestNumericObject
# My numeric object with value 1
test=TestNumericObject(1)
print float(test+1) #print 2 ( 1 + 1 ) OK , It´s called the function __add__
from my vb code
print float(test+test) #print 2 ( test + test = 1+1 ) OK , It´s called the
function __add__ from my vb code
print float(1+test)
# Error: Microsoft.Scripting.ArgumentTypeException: unsupported operand type(s)
for +: 'int' and 'TestNumericObject'
#__radd__ function is not called
Below is my vb code , basically I implemented the functions __radd__, __add__
in my vb.net code and trying to sum my objects inside python, but __radd__ is
not called.
Public Class TestNumericObject
Sub New(ByVal value As Double)
m_value = value
End Sub
Private m_value As Double
Public ReadOnly Property Value() As Double
Get
Return m_value
End Get
End Property
Public Function __float__() As Double
Return m_value
End Function
Public Function __add__(ByVal other As Object) As TestNumericObject
Dim v As Double
If TypeOf other Is TestNumericObject Then
v = CType(other, TestNumericObject).m_value
Else
v = CDbl(other)
End If
Dim o As New TestNumericObject(0)
o.m_value = Me.m_value + v
Return o
End Function
Public Function __radd__(ByVal other As Object) As TestNumericObject
Dim v As Double
If TypeOf other Is TestNumericObject Then
v = CType(other, TestNumericObject).m_value
Else
v = CDbl(other)
End If
Dim o As New TestNumericObject(0)
o.m_value = Me.m_value + v
Return o
End Function
End Class
_______________________________________________
Users mailing list
[email protected]
http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
