Getting an existing method from VSTA, then updating it

John,

The IVstaProjectHostItem will not allow you to get and update or replace a method from the VSTA project.  You can get the paths to the blueprint and the code files, but IVstaProjectHostItem does not include any way to alter or remove a method from the VSTA project.  I will look into other ways of doing this and get back to you.

Here’s a breakdown of IVstaProjectHostItem:

Represents the host item in the project.

The following tables list the members exposed by the IVstaProjectHostItem type.

Public Properties

Top

Public Methods

John,

   It is possible to get a method as a CodeDom object, update it and use the updated version; however, you may not use IVstaProjectHostItem to do this.  I checked out some MSDN forumns related to this and found a couple different options.  Here are links to the posts for you to check out directly.  I hope this helps!

-Melody

http://forums.microsoft.com/msdn/ShowPost.aspx?PostID=24860&SiteID=1

   (check out the second to last post)

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=229146&SiteID=1

msdn info on CodeDom and CodeDom.Compiler

http://msdn2.microsoft.com/en-us/library/system.codedom.aspx

http://msdn2.microsoft.com/en-us/library/system.codedom.compiler.aspx

John,

I haven't determined how to use CodeDOM for editing an existing Class and its methods.  As I see it CodeDOM is a tool that only generates code (and compiles).  CodeDOM has no way to auto-populate its graph from an existing CodeModel or 'suck in' a source file to create its graph -- again, there is no mapping from the DTE's CodeModel to a CodeDom graph. 

So the easiest way that I can see is to find your method, then remove it and replace it with the changes you require.  Below, is the code to remove a method using CodeClass.  Then you can add/insert/replace it using CodeModel (which is not language agnostic) or you can use CodeDOM to create the new method and add the new method using IVstaProjectHostItem.AddMethod(CodeMemberMethod method) as demonstrated in the VSTA SDK macro recorder samples 

Checkout EnvDTE80's; CodeClass2:

Specifically: CodeClass2.RemoveMember () and AddFunction()

When the macro recording is finished in the AdvancedCSharpShapeApp sample, SaveMacro() gets the Addin Class and uses a CodeDom.CodeMemberMethod to add a method:

hostAdapter.ProjectHostItems[0].AddMethod(method);

but prior to this, the correct CodeClass is determined by name lookup

sampleEnvDTE.CodeClass hostItemClass = FindClass(hostItemClassName, hostItemProjectItem.FileCodeModel.CodeElements);

And this is a good context to illustrate the use of AddFunction and RemoveMember:

A CodeClass instance, like hostItemClass in this example, can be used to add and remove class methods as follows:

//Add

elt = (EnvDTE.CodeElement)(hostItemClass .AddFunction(defaultName,

EnvDTE.vsCMFunction.vsCMFunctionFunction,

EnvDTE.vsCMTypeRef.vsCMTypeRefInt, -1,

EnvDTE.vsCMAccess.vsCMAccessDefault, null));

//remove

hostItemClass .RemoveMember(elt);

Here's a blog that uses EnvDTE codemodel more extensively:

http://mikehadlow.blogspot.com/2006/09/how-to-examine-code-and-write-class.html

John,

     According to the SDK, the NotImplementedException for the Parse method is thrown if the Parse and CreateGenerator methods are not overridden in the derived class, or if the Parse method is overriden and the corresponding method of the base class is called.  The CreateParser will always return null from the base implementation.  Check out your inheritence and overrides to see if this is the issue. 

-Melody

Hi John,

>>When you say that CodeDOM cannot 'suck in' a source file - do you mean that it cannot parse source >>code?

I meant to say that CodeDOM is really a one-way street.  It's not useful for editing source code.  CodeDOM cannot 'consume' source code without you implementing a source code parser and creating a CodeDOM graph.  This is probably much too complex for your purposes of 'getting an existing method and updating it'.  That is why we recommended and demonstrated the use of 'CodeModel' which should serve your purposes well enough.