Jb,
I apologize for the long delay in getting a response to you. Although this has been an interesting question, it has also been a tricky one to answer. I had to go to people in the product group directly to get their ideas. I order to avoid
some loss in translation, I'm going to copy and paste some of the ideas I collected. Please let me know which, if any, of these ideas you find most useful or promising, and if you need more clarity about them:
From "Jared":
"Why not just always create the classifier? When the project system detects a .js file being open that is a part of its system it can set a flag, add something to the property bag, etc. Until that happens the
custom classifier is a complete no-op (returns nothing, raises no events). Once that flag is set though it begins to behave normally. "
also from Jared:
"Another option is to just have a shared MEF component that is imported by both the project system and the classifiers.
interface INeedABetterName { event EventHandler Changed;
bool IsFileInProject(ITextBuffer textBuffer);
bool SetFileInProject(ITextBuffer textBuffer);
}
This service could be imported by both the classifier implementation and the project system. The classifier uses the Changed event and IsFileInProject to determine if it should be providing tags. The project system
just calls SetFileInProject for every file opened that is a part of it's project. This should be enough information to make this scenario work"
From "Dino":
"You'll probably want to set the flag in IVsProject.OpenItem. Depending on when the IClassifierProvider is called to get the classifier the "flag" might have to end up being a set of filenames where
your classifier is used. Or maybe the provider will be called before OpenItem returns in which case it could just be a static or a bool set on your IClassifierProvider which you get back to via MEF.
Another possibility (and I think a little cleaner) is that you simply implement your own editor factory and have IVsProject.OpenItem open with that editor type. A slightly more complicated version of this exists in PTVS
for Django support. There we want to open .html files with the Django editor factory and set them up with a projection buffer where we have the underlying HTML classifier doing most of the work with certain regions classified as another type. My
guess is that you could cut that code down and just create a normal editor buffer with your content type rather than setting up the projection buffer. It might be simple as getting the text buffer after it's fully initialized and changing its content
type.
You can find the PTVS source code for this at
https://pytools.codeplex.com/SourceControl/latest w/ the relevant files being DjangoProject.cs where IVsProject.OpenItem is implemented and DjangoEditorFactory where the new projection buffer is created."
Scot
Developer Support Engineer
