[IronPython] Deleting a module from the host

Curt Hagenlocher curt at hagenlocher.org
Fri Jan 4 21:32:03 CET 2008

I created and published the module myself using
ScriptDomainManager.CurrentManager.CreateModule and
ScriptDomainManager.CurrentManager.PublishModule.  Hmm... I just noticed for
the first time the naming inconsistency there between "Module" and

To back up a step, I'm trying to TDD an integration layer between a C# app
and some Python components, and I want to be able to basically "undo" the
test actions so it won't influence the next test.  If I understand the
recent DLR hosting docs correctly, at some point I should be able to
accomplish the same thing by creating new ScriptRuntimes instead -- but it
looks like IronPython is not yet close to allowing this.
When you consider that there might be published ScriptScopes in many
different languages then, yeah, it really complicates the potential
relationship between the "global object" (that's global per runtime, yes?)
and sys.modules.  I would certainly want to be able to use DLR modules
(sorry, "ScriptScopes") from Python without worrying about their
implementation language.  How can I get a reference to them if not through
sys.modules?  How do they get loaded in the first place?  What's role does
the Python loader and its extensibility mechanisms play when Python code
causes a Javascript module to be loaded?

Plenty of fun questions!

On Jan 4, 2008 9:23 AM, Dino Viehland <dinov at exchange.microsoft.com> wrote:

>  Unfortunately the answer is it depends, and it's probably not supported
> in Alpha 7 L
> The depends part is how the module got there and it all revolves around
> the design we've come up with for the hosting of multiple languages.  We
> have a global object per ScriptRuntime which is (currently) a ScriptScope.
> That scope holds onto a bunch of name/value bindings (where a value could be
> another nested ScriptScope) and this is the closest concept (in the DLR) we
> have to a module.  The idea then is that each language exposes the global
> object via its own mechanism picking something that makes the most sense for
> that language.  IronPython is going to expose the global object via import
> much like it exposes other modules and .NET namespaces.  But that doesn't
> mean sys.modules goes away, or that sys.modules becomes the global
> object.  Instead what we're currently planning on doing is having import
> fallback to the global object just as it falls back to the namespaces today.
> (As I type this I realize it does complicate this scenario – so I'll ask if
> this sound crazy or like a bad idea?  Should we instead try to merge them
> and have sys.modules == global object?  That has its own potential quirks
> but they could be dealt with.)
> So that gives two different locations where modules can be published:
> Either in the global object or in sys.modules.  Therefore how you added
> the module effects how the module gets removed.  If the user did "import
> foo" and we pulled up a .py file it'll end up being in sys.modules.  If we
> pulled up a .js file from the DLR then it'll be in the global object.
> Further complicating things is the fact that the global object isn't
> really implemented yet.  There's some remnants of the old cross-language
> module support we had early on but that's not really the global object.  So
> for now in Alpha 7 I think the answer is that you execute the code.
> There's also one more future possibility: And that is that to expose
> Python specific functionality we may need to have a PythonEngine class or
> something that lets you do things that aren't part of the least common
> denominator.  There accessing sys.modules would be a likely piece of
> functionality to have.
> *From:* users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com]
> *On Behalf Of *Curt Hagenlocher
> *Sent:* Friday, January 04, 2008 6:03 AM
> *To:* Discussion of IronPython
> *Subject:* [IronPython] Deleting a module from the host
> In a previous alpha of IPY 2.0, I deleted modules by saying
> PythonEngine.CurrentEngine.SystemState.modules.Remove(moduleName)
> (which is almost a direct analog of "del sys.modules[moduleName]").
> What's the best approach in Alpha 7?  And will this change as IronPython
> continues to migrate to the DLR?
> I suppose I could literally execute Python code to do what I want, but it
> seems so inelegant...
> --
> Curt Hagenlocher
> curt at hagenlocher.org
> _______________________________________________
> Users mailing list
> Users at lists.ironpython.com
> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
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