[Ironpython-users] PythonAst

Rutger Koperdraad r.koperdraad at exchangeit24.com
Mon Dec 19 16:38:58 CET 2011

Hi Dino,


Thanks a lot. It's working reasonably well now. It would be nice to have
more comprehensive documentation of these classes, as it is quite a hassle
to extract the variables. I'm now extracting the assignment statements from
the script, but excluding those that are inside function bodies. In the
expression, I get al name expressions and then remove the function names
(call expressions targets) and the global variables. Thanks a lot for your


With best regards,

Rutger Koperdraad


The ExchangeIt Support Team


Description: cid:image001.jpg at 01C8455E.47D3E2D0


EUR:        O:  +31 (0)20 893 2601           |  F:  +31 (0)172 413 746   

USA:        O:  +1 (925) 208 4716


Support request only via our online support ticket system at
<http://www.exchangeit24.eu/> www.ExchangeIt24.eu 

SALES:      <mailto:Sales at ExchangeIt24.com> Sales at ExchangeIt24.com

WEB:        <http://www.exchangeit24.eu/> www.ExchangeIt24.eu  

FORUM:   <http://www.cardexchange.eu/> www.CardExchange.eu


... Solving today's card production problems, with tomorrow in mind!


lversion.html> Click here to download a FREE trial version


This email and any files transmitted with it are confidential and intended
solely for the use of the individual or entity to whom they are addressed.
If you have received this email in error please notify the system manager.
This message contains confidential information and is intended only for the
individual named. If you are not the named addressee you should not
disseminate, distribute or copy this e-mail. Please notify the sender
immediately by e-mail if you have received this e-mail by mistake and delete
this e-mail from your system. If you are not the intended recipient you are
notified that disclosing, copying, distributing or taking any action in
reliance on the contents of this information is strictly prohibited.


From: Dino Viehland [mailto:dinov at microsoft.com] 
Sent: Thursday, 15 December, 2011 14:07
To: Rutger Koperdraad; ironpython-users at python.org
Subject: RE: [Ironpython-users] PythonAst


I'd suggest adding a method in the walker which handles AssignmentStatements
and looks to see if the left-hand side is a NameExpression.  If it is then
you can add it to a list of excluded variable names which you can remove
from clnVariableNames after the walk is finished.


From: ironpython-users-bounces+dinov=microsoft.com at python.org
[mailto:ironpython-users-bounces+dinov=microsoft.com at python.org] On Behalf
Of Rutger Koperdraad
Sent: Thursday, December 15, 2011 8:34 AM
To: ironpython-users at python.org
Subject: [Ironpython-users] PythonAst




I'm writing an application in Visual Basic .NET that allows the users to
write scripts in IronPython for some specialized customization needs. Users
provide a script, a number of variable names and values, and an expression.
For example, to customize the displaying of dates, they could provide the
following script, variables and expressions:



dateformat = 'dddd d MMMM yyyy'

prefix = 'Birth date: '


def format(d):

  import System

  dd = System.DateTime.Parse(d)

  return dd.ToString(dateformat)



birthdate = '10/04/1968'



prefix + format(birthdate)


In Visual Basic .NET I create a ScriptRuntime, ScriptEngine, ScriptSource
and ScriptScope. I add the variables to the ScriptScope, execute the script
and evaluate the expression. That's working like a charm.


I would like to add functionality that automatically detects which variables
need to be defined. In the above example, I would like the user to specify
the script and the expression and the software to detect that the variable
"birthdate" is needed and prompt for a value. I tried to do so with
PythonAst, but I cannot find sufficient documentation on internet to get it
working in general. The functions below work to some extent. They get all
the names from the expression and then remove "format" for being a function
name and not a variable name. But this function still returns "prefix",
which it shouldn't. Any help or documentation would be appreciated.


    Public Function GetVariableNames(ByVal strExpression As String) As


            If Not String.IsNullOrEmpty(strExpression) Then


                ' Create a script runtime if needed

                If m_objScriptRuntime Is Nothing Then

                    m_objScriptRuntime =

                End If


                ' Create the objects needed by the expression walker

                Dim objEngine As ScriptEngine =

                Dim objSource As ScriptSource =

                Dim objSourceUnit As SourceUnit =

                Dim objLanguageContext As LanguageContext =

                Dim objCompilerContext As New CompilerContext(objSourceUnit,
objLanguageContext.GetCompilerOptions(), ErrorSink.Default)

                Dim objParser As Parser =
Parser.CreateParser(objCompilerContext, New PythonOptions)

                Dim objPythonAst As PythonAst =

                Dim objExpressionWalker As New ExpressionWalker


                ' Determine the variable names

                Call objPythonAst.Walk(objExpressionWalker)


                Return objExpressionWalker.VariableNames

            End If

        Catch ex As Exception

            Call LogException(strExpression, ex)

        End Try


        Return New StringCollection

    End Function


    Private Class ExpressionWalker

        Inherits PythonWalker


        Private clnVariableNames As New StringCollection


        Public ReadOnly Property VariableNames As StringCollection


                Return clnVariableNames

            End Get

        End Property


        Public Overrides Sub PostWalk(node As NameExpression)

            Call clnVariableNames.Add(node.Name)


            Call MyBase.PostWalk(node)

        End Sub


        Public Overrides Sub PostWalk(node As CallExpression)

            Dim objNameExpression As NameExpression = TryCast(node.Target,


            If Not objNameExpression Is Nothing Then

                Call clnVariableNames.Remove(objNameExpression.Name)

            End If


            Call MyBase.PostWalk(node)

        End Sub


    End Class


With best regards,

Rutger Koperdraad.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/ironpython-users/attachments/20111219/07af64d8/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 2282 bytes
Desc: not available
URL: <http://mail.python.org/pipermail/ironpython-users/attachments/20111219/07af64d8/attachment.jpg>

More information about the Ironpython-users mailing list