The Builder API is a set of functions that can be used in control scripts when executing the builder from the command line. This allows you to create scripts that can be passed on the command line that modify your installer based on criteria.
Calling a Builder API proc
All of the procs in the Builder API are in the ::BuilderAPI namespace. To call a proc in the Builder API, simply use the fully-qualified name of the proc in your code. All arguments passed to an Builder API proc are non-positional key-value pairs. That means that it doesn't matter what order you pass the arguments in since each argument is specified as a -option with a value.
For example, let's say we wanted to change the name of the installer produced for the Windows platform in a certain case. You would add something like this to a control script:
::BuilderAPI::SetPlatformProperty -platform Windows -property Executable -value "setup.exe"
In this example, we call the proc ::BuilderAPI::SetPlatformProperty with three arguments: -platform, -property and -value. Each property must have a value after it.
Finding the arguments to an API call
All API calls are loaded into the install builder when it loads, so you can easily go into the console (through the Help->Show Debug Console menu) and type a Builder API call to see what it can do. To see the usage for an API call, type the name of the call and the argument -? into the console. Like this:
This will dump the usage information, including all possible arguments, for the ::BuilderAPI::SetPlatformProperty API call. Of course, you can always read the documentation for each call as well, but this might be quicker for some people.