Monday, August 25, 2008

Applying good software development practices to VBA and MS Access (and tools, too!)

After working with TSQL almost exclusively for the last six months the time came last month where I had to make code changes to a Microsoft Access front-end application at work.

Based on what I have learned in the past several years or so regarding software development in .NET, I decided to arm myself for tackling legacy code in a platform and language notoriously known for not being ideal for software development.

IDE Tools

I accidentally came across MZ-Tool a plugin for the VB Editor IDE and wow! This made all the difference in the world. It was nice to find a free tool to inject a little ReSharper-ish support into the rigid VBA IDE. The product apparantly started in the VB\VBA world and when .NET came along it was ported to Visual Studio.NET. (It can actually be considered as a direct competitor to Re#. Note that the .NET version is not free.)

Here are the features I was using actively during coding:
  • Replace In All Projects- This was huge in that it allowed me to actually perform the refactoring technique, 'Rename', with various levels of control. What really made it possible is the actual visual tree view of your code where the text you want to change shows up as well as showing what function/sub where it can be find under. I was not afraid to actually change names of things that were either goofy, confusing or antiquated in coding style into much more meaningful names. In the end, I had significantly less fear in breaking code. (This feature is equivalent to Re# 'Find Usages Advanced')
  • Procedure Callers- Similar to Re# 'Show all usage" for a method or variable (and it's also navigable via a visual tree view)
  • Code Templates- This allows me to create and permanently store boilerplate code that I needed for testing code using VBLiteUnit (see next section). This feature opened my eyes to more actively use and create with 'Live Templates' in Re#.
  • Add Procedure- Slick and fast way to create more boiler-plate code for procs/func.
  • Add Error Handler- This was a gift from the heavens. Being able with a simple keystroke drop in code for error handling in any sub/function. Error handling is horrible in VB/VBA so this significantly helped in reducing the pain.
  • Add Module Header and Add Procedure Header- It's just like having GhostDoc. Adding comments is very important in legacy code.
  • Sort Procedures -Helps organize your code. It is equivalent to Re#'s 'File Structure Popup' which I use all the time for the same reasons: drag-n-drop your code to how you see fit.
  • Private Clipboard- This can be big in legacy code and in a language where you do end up with a lot of cutting and pasting. Actually, better than Re#'s version because you can actually control what is stored in it and can retain it for as long as you like within the duration of your session.
  • Review Source Code- A extremely limited version of code analysis in Re#. It only tells you if a variable, constant, procedure is not being used. But good nonetheless to clean up your code and get rid of cruft.
The following features were interesting but less used day to day:
  • Generate XML Documentation- produces a very nice readable xml doc about your code comparable to XML CHM output in VS
  • Statistics- You can actually see how your lines of code is distributed in your code base.
The one thing I wish MZTools had which IMHO I consider to be one of the two most important refactoring techniques is 'Extract Method' ('Rename Method' being the other). If it had that it would be quite the rock solid refactoring tool for VBA. Nonetheless, MZTool just like Re# in Visual Studio has given me control over my code instead of the code controlling me.

Unit Testing

Being a dedicated practitioner of Test Driven Development (TDD), this was important for me to do on a lot levels. After looking at two options I settled on VBLiteUnit because it is extremely lightweight and the ramp up learning time is short especially if you are familiar with any of the other xUnit frameworks (which is exactly what the author intended in creating it hence the word "Lite" in its name. My belief is that the author might have thought that the existing one out there, VBAUnit, was too bulky and cumbersome to use and maintain. Definitely a much more "pragmatic" and "agile" approach in his solution.)

The author decided to use the VB construct 'Select Case' (think 'Switch') with each leg of your 'Case' defining an individual test. Impressively it works really well (and added bonus is that your test descriptions can be more descriptive and natural in tone because it's just string text. Interesting to note as compared with a blog post on Unit Test Naming Conventions written by a developer I used to worked with)

To implement my new changes, as expected, I did have to do some refactoring of the code that required to be touched. This generally resulted in new testable classes but I had TDD with VBLiteUnit (and MZTools) to lead the way.

All in all it was very satisfying to be able to actually do TDD in Access/VBA. It gave me that same feeling that I get when doing TDD in C#. The platform for a moment felt much more real as software development than it ever had before.


Some lessons were learned of course ("evolve or die"). If you have no choices, resources, etc. in a situation no matter how "trivial" then you still attack your problem 100%. Why? Because you not only get to apply and transfer knowledge and techniques to another area of software development but also you might actually learn some new things that you can in turn use later on. For example,
  • I started using the Immediate Window much more now in Visual Studio.
  • I started using features in Re# that I had not used or dismissed before (like the live templates, copy clipboard, etc.)
  • Design patterns can still be used even with what some might consider a "rudimentary" language. For example, I was actually able to implement a variation of the Repository pattern (ala Eric Evan's DDD) that hydrated a domain object and make it work. Hence if you understand design patterns and how to use them then it does not matter what OO language you are using.
However, I can see why VB developers don't know OOP. One good reason is that VB is lacking in some key features of an OOP language. The biggest one in my opinion is that it does not support implementation inheritance. That was frustrating because I was trying to use a technique that Michael Feathers described in his book, Working Effectively with Legacy Code, to test legacy code. That entails creating a seam in your code by inheriting and then overriding an external dependency. Unfortunately, VB simply just enforces the interface contract but does not carry over the implementation code from the base class to its derived ones.

Nonetheless, using VBA with VBUnitLite and MZTools had actually turn out to be a much more gratifying and, yes, may I even say aloud, "fun" experience than I expected. The main reason beyond the more obvious such as being to do TDD was that I was doing so much TSQL just prior that is was like being transported out of the stone ages. The TSQL language and Microsoft's IDE for it (SQL Server Mgt Studio) was so frustrating to use that working back in a programming language designed for applications even as "minor/toy" and with so much stigma as Access VBA was such a breath of fresh air and extremely invigorating (It was like giving a tablespoon of water to a very thirsty person).

TSQL was and still is such a struggle even with TSQLUnit. It has so much limitations when it comes to creating flow logic, reusable code, and testability. (Granted it is a DSL specialized and intended for manipulation of data and its storage structure but I feel like that the SQL language has not really evolved much in its odd 30 years of existence. In areas that it has changed it ends up resembling other non-SQL languages so what's the point? Perhaps it's time for a better replacement language(s)?) In the future, any application developer that I encounter again who says "sprocs are the way to go" will get an earful and maybe more.

TSQL is so painful in its existing form that, believe it or not, I rather be working in VBA than in TSQL if those were my only options!! I know that sounds crazy and shocking but that's how much I prefer not to have to do database development and deal with TSQL. I'll leave it to the folks who actually enjoy it. But sadly it is the bulk of my work these days. (The one thing I do like about it is it's language support for "dynamic SQL" but that is not enough of a motivation for me.)

Who knows? I went from C# --> SQL --> VBA --> SQL in the last six months. If I had gone from C# --> VBA I probably would have a different opinion and experience. Hard to tell in retrospect.

Don't worry I still do C# and have been doing it for the last six months in parallel on side projects and supporting processes at work. Unfortunately, I am back to doing TSQL for the next several months. Aargh!!!

Final Thoughts

What was the point of all of this other than to rant on about a language no one cares about if you consider yourself a "serious" programmer? Well, just like VB6, Microsoft plans on retiring VBA and possibly allowing Office apps to be supported by any.NET language including C#!! Therefore, the tools mentioned above are "dead" in the sense no new development is going be done on them especially that their respective authors have appeared to have moved on from doing any new releases.

IMHO, I think what Microsoft really should do is to allow dynamic languages to support their Office apps. That is where dynamic languages (ex. Ruby, Python, BOO, etc.) seem like such a natural fit and obvious for the nature of that work. Just imagine you can write code very quickly with ever-changing requirements and it does not have to perform fast (as compared with statically typed languages.) Seems like such a "no-brainer". (maybe in the far, not-too-distant future, power users could even be writing MS Excel or Word macros in F#? Just imagine that!)

1 comment:

Anonymous said...

MZ-Tools 8.0 was released recently, fixing a few bugs and introducing new features - I haven't tried it but from a quick look at the download page it seems to no longer be free.

Have you seen/tried Rubberduck?

The tool has been dubbed "R# for VBA" quite a few times on Twitter already, and upcoming version 2.0 looks very, very promising. The add-in is free and open-source, under active development, created by some of the top users of Code Review Stack Exchange (, and includes code inspections (and quick-fixes), rename, extract method, reorder parameters, remove parameter, and another upcoming half-dozen refactorings; unit testing, IDE-integrated Git source control, and an upcoming port/rewrite of the popular Smart Indenter add-in.

Last release 1.4.3 has a number of known issues, but 2.0 is on its way.

Just sayin' ;-)