Custom parameters
Applies to: 
Visual Studio 
Visual Studio for Mac
Note
This article applies to Visual Studio 2017. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here
Custom parameters control the operation of a wizard after a wizard has started. A related .vsz file provides an array of user-defined parameters that are packaged by the integrated development environment (IDE) and passed to the wizard as an array of strings when the wizard is started. The wizard then parses the array of strings and uses the information to control the actual operation of the wizard. In this manner, a wizard can customize functionality depending on the contents of the .vsz file.
Context parameters, on the other hand, define the state of the project when the wizard is started. For more information, see Context parameters.
Following is an example of a .vsz file that has custom parameters:
VSWIZARD 8.0
Wizard=VsWizard.VsWizard_Engine
Param="WIZARD_NAME = Sample Wizard"
Param="WIZARD_UI = FALSE"
Param="RELATIVE_PATH = VSWizards\Classwiz\ATL"
Param="PREPROCESS_FUNCTION = CanAddATLSupport"
Param="PROJECT_TYPE = CSPROJ"
The author of the .vsz file adds the values of the parameters. When a user selects New Project or Add New Item on the File menu or by right-clicking a project in Solution Explorer, the IDE collects these values into an array of strings. The IDE then calls the project's AddItem method with the VSADDITEMOPERATION flag set, and the project calls the RunWizardFile method that is responsible for running the wizard and returning the result.
The wizard is responsible for parsing the array of strings and acting on the strings appropriately. In this manner, by implementing custom parameters you can create one wizard that performs a variety of functions. In other words, one wizard could have three different .vsz files. Each file passes different sets of custom parameters to control the behavior of the wizard in various situations.
For more information, see Wizard (.vsz) file.