[IronPython] Access to current Python engine in C# (Silverlight)

[Michael Foord]

Jimmy Schementi wrote:
>> Jimmy - did you get a chance to look at this?
>>     
>
> Yes, sorry for the wait. Given something.py:
>
> class Foo(object):
>   attribute = "weeee"
>
> The following will import it using the hosting API (written in Python because I don't have the SL tools installed at the moment):
>
> code = """
> import something
> """
> runtime = DynamicApplication.Current.Runtime;
>
> engine = runtime.GetEngine("Python")
> scope = engine.CreateScope()
> script = engine.CreateScriptSourceFromString(code, SourceCodeKind.Statements)
> script.Execute(scope)
> scope.something.Foo.attribute
> # => weeee
>
> Here's a repro of the behavior (run with script/server)
> http://jimmy.schementi.com/silverlight/sl-py-import.zip
>
>   

Code basically identical to this but in C# fails on the import. This is 
even when the C# code is actually being called *from* Python - so the 
DLR has definitely already executed some Python code.

>> If the code shown below *genuinely* gets a reference to the current engine then shouldn't the search path be setup already?
>>     
>
> No, unfortunately the search path is set by DynamicApplication.InitializeDLR, which is only called when DynamicApplication is doing the code execution. I can make the search path be set in DynamicApplication.CreateRuntimeSetup, and then this should work fine. So even if you get DynamicApplication.Current.Runtime, if DynamicApplication hasn't run DLR code yet (which would be the case in a C#/VB hosted environment) you'll need to do:
>
> runtime.Setup.Options["SearchPaths"] = new string[] { String.Empty };
>
>   
 
I'll try this. As I mentioned I assumed that an already initialised 
engine (that had already executed Python code) would not need it.



> The above example doesn't need this since it's written in Python, so DynamicApplication has run code and the search path has already been set. I can verify this works from C# as well, but let me know if you still have problems.
>
> Was there any other SL questions you had? I have a bunch of emails starred but I'm not sure if they were all about this.
>
>   

The other scenario in which import doesn't work is the following code:


using System;
using System.Collections.Generic;
using System.Text;


using IronPython.Hosting;
using IronPython.Runtime;
using IronPython.Runtime.Types;

using Microsoft.Scripting;
using Microsoft.Scripting.Hosting;
using Microsoft.Scripting.Runtime;


namespace ExecutePython
{
   public class ExecutePython
   {
       static string code = @"
class Foo(object):
   attribute = 'weeeee'

";
       public static Scope CreateModule(CodeContext context)
       {
           PythonContext python = PythonContext.GetContext(context);

           PythonDictionary globals = new PythonDictionary();
           globals["__name__"] = "AModule";
           Scope module = new Scope(globals);
           SourceUnit script = python.CreateSnippet(code, 
SourceCodeKind.Statements);
           script.Execute(module);
           return module;
       }
   }
}



Michael Foord



> ~Jimmy
>
> -----Original Message-----
> From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Michael Foord
> Sent: Sunday, May 17, 2009 8:27 AM
> To: Discussion of IronPython
> Subject: Re: [IronPython] Access to current Python engine in C# (Silverlight)
>
> Jimmy - did you get a chance to look at this?
>
> If the code shown below *genuinely* gets a reference to the current engine then shouldn't the search path be setup already?
>
> Can you see what is wrong with the code below?
>
> Thanks
>
> Michael
>
> Michael Foord wrote:
>   
>> Hello guys,
>>
>> I have a second use case for embedding IronPython in Silverlight. This
>> is actually a dynamic application with a C# component that needs to
>> programattically build a Python module.
>>
>> Again I have the same problem - imports in Python code fail. I would
>> have expected that accessing the current runtime and fetching a Python
>> engine would fetch the current Python engine, with the browser host
>> correctly setup. Unfortunately that seems not to be the case. Can
>> anyone spot problems with the following code:
>>
>>
>> using Microsoft.Scripting.Silverlight; using IronPython; using
>> IronPython.Hosting; using Microsoft.Scripting; using
>> Microsoft.Scripting.Hosting;
>>
>> namespace EmbeddedSLModule
>> {
>>    public class EmbeddedSLModule
>>    {
>>        private static string source = @"
>> import something
>> ";
>>        public static ScriptScope GetModule(){
>>            ScriptRuntime runtime = DynamicApplication.Current.Runtime;
>>            ScriptEngine engine = runtime.GetEngine("Python");
>>            ScriptScope scope = engine.CreateScope();
>>            ScriptSource script =
>> engine.CreateScriptSourceFromString(source, SourceCodeKind.Statements);
>>            script.Execute(scope);
>>
>>            return scope;
>>
>>        }
>>    }
>> }
>>
>>
>> It works fine for code that doesn't import anything - but imports from
>> within the xap file fail.
>>
>> Thanks
>>
>> Michael Foord
>>
>>     
>
>
> --
> http://www.ironpythoninaction.com/
> http://www.voidspace.org.uk/blog
>
>
> _______________________________________________
> Users mailing list
> Users at lists.ironpython.com
> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
>
> _______________________________________________
> Users mailing list
> Users at lists.ironpython.com
> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
>   


-- 
http://www.ironpythoninaction.com/
http://www.voidspace.org.uk/blog