Mod the Machine

Working with Files and Directories

Here’s some more functionality I’ve discovered in the .Net Framework that makes it hard for me when I have use VBA.  In a recent post I talked about the functionality to manipulate full paths that’s supported by the Path class of the System.IO namespace.  Two other very useful classes supported by System.IO are Directory and File.  In VBA there are several functions that work with files but they’re harder to use and don’t have the same capabilities as what’s supported by System.IO.

A workhorse function in VBA is the Dir function.  You can use it to check for the existence of a file.  This isn’t much code but it’s not particularly intuitive that you can use Dir for this.

Dim filename As String
filename = "C:\Temp\Part1.ipt"
If Dir(filename) = "" Then
    MsgBox "Specified file does not exist."
Else
    MsgBox "File exists."
End If

Using VB.Net and System.IO I can accomplish the same thing with the code below.  In lines of code there’s not any difference, but it’s easier to understand what it’s supposed to be doing.

Dim filename As String
filename = "C:\Temp\Part1.ipt"
If System.IO.File.Exists(filename) Then
    MsgBox("File exists.")
Else
    MsgBox("Specified file does not exist.")
End If

The File class that’s used above supports much more than just the Exists function.  You can delete, open for read, create, get and set various file attributes, etc.

In addition to the File class the System.IO class also supports the Directory class.  Using this class you can check for the existence of a directory, create a directory, delete a directory and much more.  Here’s a VBA example using the Dir function to iterate over all of the part files within a directory.  This does the job but isn’t particularly intuitive.  If you also want to process the contents of subdirectories then it gets much more complicated because you can’t have nested Dir calls.

Public Sub ProcessPartsVBA()
    Dim processPath As String
    processPath = "C:\Temp\"

    ' Get the files in the specified directory.  
    Dim filename As String
    filename = Dir(processPath & "*.ipt")
    Do While filename <> ""
        Debug.Print "Processing " & processPath & filename

        filename = Dir
    Loop
End Sub

Here’s the same thing using the Directory class.  Here a single call to the GetFiles function returns all of the files matching the search pattern as an array of strings.  I think this is much easier to read, maintain, and is more flexible.

Public Sub ProcessPartsVBNet()
    Dim processPath As String
    processPath = "C:\Temp\"

    ' Get the files in the specified directory.
    Dim filenames() As String
    filenames = System.IO.Directory.GetFiles(processPath, "*.ipt")
    For Each filename As String In filenames
        Debug.Print("Processing " & filename)
    Next
End Sub

There’s also a version of the GetFiles function that gets the files in the current directory and all subdirectories.  This is messy to do with VBA.

Public Sub ProcessAllPartsVBNet()
    Dim processPath As String
    processPath = "C:\Temp\"

    ' Get the files in the specified directory and subdirectories.
    Dim filenames() As String
    filenames = System.IO.Directory.GetFiles(processPath, _
                          "*.ipt", SearchOption.AllDirectories )
    For Each filename As String In filenames
        Debug.Print("Processing " & filename)
    Next
End Sub

Inventor API Virtual Training Videos

We recently finished presenting the first set of API virtual training sessions.  It seems they were a success since those attending want us to continue with the rest of the material.  The sessions were presented by myself and members of the Autodesk DevTech team.  They’re the guys that support the members of the Autodesk Developer Network (ADN).  If you want to get serious about developing with Inventor, or any Autodesk product, it’s worth investigating if a membership makes sense for you. 

Here are links to the material from the classes presented so far. 

Module 01 – Basic concepts

Module 02 – Common Document Functionality

Module 03 – Part Documents

Module 04 – BREP

Module 05 – Sheet Metal

Module 06 – Assembly Documents

Module 07 – Drawing Documents

Module 08 – .Net Add-Ins

Module 09 – User Interface

Module 10 – Events

If you’re interested in this series continuing contact Gary Wassell (DevTech manager) and let him know.

API Wishlist Survey

It’s time again for the latest API wishlist survey.  This survey provides an opportunity for us to get some information about who’s using Inventor’s API and what issues you’re having.  This information is very important in helping us to determine what to spend resources on for the upcoming releases.

Please take the time to think about any issues you’re having with the API; what functionality that you need is missing or what tools or documentation would make your life much easier.  This years survey is more open than it has been in the past to allow you to describe your specific issues rather than feel limited to choosing from a predefined list.

You can access the survey here: Autodesk Inventor® Survey. 

The survey will remain open until May 30th, 2010.  Thanks in advance for your input.

If you use other Autodesk products and their API’s, there are also API surveys for them.  You can find more info about all the surveys at Kean Walmsley’s Through the Interface blog.

Autodesk University Class Proposals (Last Call)

You have one more week to submit your proposals for this years Autodesk University.  They’re due May 14th.  I’ve been dragging my feet and just submitted mine this morning.  More information is available at the Call for Proposals site.  Hopefully I’ll see you in Las Vegas this November, either as a speaker or an attendee.

Using VBA Sample Code (for the Non-Programmer)

You don’t know anything about VBA but you’ve found some interesting VBA code somewhere on the web, in a newsgroup, or maybe even here.  So now what do you do with that code to be able to use it in Inventor?  Here are the cookbook steps:

1. From within Inventor, press Alt-F11 or run the VBA Editor command from the Tools tab of the ribbon.  This will open the VBA development environment, as seen below.

   

2. The Project Explorer is the window containing the tree at the upper-left in the picture. 
   • Expand the node labeled “ApplicationProject”. 
   • Expand the node labeled “Modules”
   • Double-click on the node labeled “Module1”
     An editor window will pop-up, similar to the picture below. (In the picture below I have one document open so there are two top-level nodes in the project explorer.  One node is for the application project and the other node is for the document.  Make sure you use the application project.)
     
   

3. Go to wherever the original VBA code is (browser, new reader, email, etc.) and copy it to the clipboard.
   
4. Click within the VBA code window and paste the code.  You should see something similar to the picture below.

   

5. Scan through the code to see if there are any problems.  Do this by scrolling down through the pasted code looking for any red lines.  If you don’t see any problems go to step 6, otherwise continue with this step.

   The most common issue when pasting code is that lines that should be a single line may end up wrapping onto two lines.  VBA expects a statement to be on a single line.  The example below illustrates the problem where what should be a single line has been broken and wraps onto the next line.

   

   Fix it by editing it so it is on a single line.

   There’s also an exception to the statement I made above about the requirement of a statement only being a single line.  It’s possible to break a statement into multiple lines by adding a “ _” (space and underscore) at the end of a line.  This is a line continuation character and indicates that the statement continues on the next line.  That’s shown in the top statement in the previous picture.  You may need to understand that to better understand why a line is shown in red.
   
   If you see other problems, it beyond the scope of this post to diagnose those.  It would be best to go back to the author or to ask someone that has some familiarity with the API.

6. Close the VBA window.
   
7. Run the program by pressing Alt-F8 or running the Macros command from the Tools tab.  This will display the Macros dialog, as shown below.

   

8. In the “Macros in” drop-down list select “Application Project” and choose the macro you want to run from the list, as shown below.

   

9. Click the “Run” button.

For some other ways to execute a macro see the post Creating Buttons for VBA Macros.

Working with Filenames

It’s common to need to manipulate filenames within a program.  When using VBA there’s very little built-in functionality to help with this.  When using VB.Net I had assumed I needed to do the same thing there that I had been doing in VBA.  It wasn’t until fairly recently that I discovered a set of utilities in the .Net Framework that makes working with filenames much easier.

The .Net Framework is one of the huge advantages of doing development with any of the .Net languages.  Especially compared to VBA which has very little built-in functionality.  As I find things in the .Net Framework I find useful I’ll add blog posts in case some of you are like me and are still discovering its capabilities.

For those of you using VBA, here are some functions that I wrote to work with filenames.  Using these I can extract the various bits of a filename and piece it back together to get the new filename I need.

' Return the path of the input filename.
Public Function FilePath(ByVal fullFilename As String) As String
    ' Extract the path by getting everything up to and
    ' including the last backslash "\".
    FilePath = Left$(fullFilename, InStrRev(fullFilename, "\") - 1)
End Function


' Return the name of the file, without the path.
Public Function Filename(ByVal fullFilename As String) As String
    ' Extract the filename by getting everything to
    ' the right of the last backslash.
    Filename = Right$(fullFilename, Len(fullFilename) – _
               InStrRev(fullFilename, "\"))
End Function


' Return the base name of the input filename, without
' the path or the extension.
Public Function BaseFilename(ByVal fullFilename As String) As String
    ' Extract the filename by getting everttgubg to
    ' the right of the last backslash.
    Dim temp As String
    temp = Right$(fullFilename, Len(fullFilename) – _
           InStrRev(fullFilename, "\"))

    ' Get the base filename by getting everything to
    ' the left of the last period ".".
    BaseFilename = Left$(temp, InStrRev(temp, ".") - 1)
End Function


' Return the extension of the input filename.
Public Function FileExtension(ByVal fullFilename As String) As String
    ' Extract the filename by getting everthing to 
    ' the right of the last backslash.
    Dim temp As String
    temp = Right$(fullFilename, Len(fullFilename) – _
           InStrRev(fullFilename, "\"))

    ' Get the base filename by getting everything to
    ' the right of the last period ".".
    FileExtension = Right$(temp, Len(temp) - InStrRev(temp, ".") + 1)
End Function


' Test the filename functions.
Public Sub TestFileFunctionsVBA()
    Dim fullFilename As String
    fullFilename = "C:\Samples\Models\Parts\OilPan\OilPan.ipt"
    Debug.Print FilePath(fullFilename)
    Debug.Print Filename(fullFilename)
    Debug.Print BaseFilename(fullFilename)
    Debug.Print FileExtension(fullFilename)
End Sub

Below are the results as seen in the Immediate window.

C:\Samples\Models\Parts\OilPan
OilPan.ipt
OilPan
.ipt

Using VB.Net this is all much easier.  The .Net Framework supports the IO class which has a lot of file related functionality.  For working with file paths the IO class provides access to the Path class.  Below is a VB.Net function that does the same thing as the VBA code above but it uses .Net Framework functions instead of custom functions.  You’ll need to use the Imports statement for System.IO or specify the full namespace path as demonstrated in the GetDirectoryName call below.

Imports System.IO

' Test the .Net Framework Path functions.
Public Sub TestFileFunctionsVBNet()
    Dim fullFilename As String
    fullFilename = "C:\Samples\Models\Parts\OilPan\OilPan.ipt"
    Debug.Print(System.IO.Path.GetDirectoryName(fullFilename))
    Debug.Print(Path.GetFileName(fullFilename))
    Debug.Print(Path.GetFileNameWithoutExtension(fullFilename))
    Debug.Print(Path.GetExtension(fullFilename))
End Sub

As you can see the results are identical to the VBA sample without having to write the custom functions.

C:\Samples\Models\Parts\OilPan
OilPan.ipt
OilPan
.ipt