In previous versions of the Visual Studio the build customizations were basically limited to a PreBuildEvent and a PostBuildEvent. Now we have MSBuild which allows for many very specific and complex build customizations. But Microsoft obvioiusly must continue to support the Pre/Post build event. It is something that already exists, many people are familiar with it, and its very simple. Let’s see how this is implemented within MSBuild. If you add a Pre or Post build event from Visual Studio, then examine yore project file you’ll find something like the following declared.

  <PropertyGroup>

    <PostBuildEvent>echo 'This is the post build event!'PostBuildEvent>

  PropertyGroup>

So these events are actually simple properties that will be executed when the time is right. What does this mean for you? Now lets talk about what’s funny about this. When MSBuild loads your project file it will load all of the properties contained in PropertyGroup elements, followed by that your items will be evaluated. What this means for the Pre/Post build event is that you are able to access properties that have been declared in PropertyGroup element before the Pre/Post build event declaration. After this evaluation is made the value for the Pre/Post build event will not change! What this equates to is that you are able to use properties such as OutDir or AssemblyName, but you’ll never be able to access properties that are created from tasks contained in other targets! If you need to access properties that have been created by other targets then you’ll have to extend your build process outside of the Pre/Post build event. This is outlined in my MSDN article Inside MSBuild in the Extending the Build Process section.

This entry was inspired by a post on the MSDN MSBuild forum.

Sayed Ibrahim Hashimi