IDL’s preference system allows developers, administrators, and individual users to control default values for many aspects of IDL’s environment and configuration. Creators of runtime applications can take advantage of the preference system to customize the environment in which a particular application runs.

See Preferences for Runtime Applications for a discussion of using preferences in the context of any IDL runtime application, including applications that run in the IDL Virtual Machine.

The process of specifying preferences for a Virtual Machine application is complicated by the following facts:

  • Since you are relying on a standard IDL Virtual Machine distribution rather than a distribution you create, it is more difficult to install a preferences file in the application distribution.
  • On Microsoft Windows and Mac platforms, users may launch your Virtual Machine application by clicking on the SAVE file icon, or by dragging the SAVE file icon onto the Virtual Machine icon. This prevents you from specifying preferences via a command line option.

Options for Windows Applications

If your Virtual Machine application runs under Microsoft Windows, you have the following options:

  • Have your users launch the Virtual Machine application via the Windows command line, and use the -pref command line option to specify a preferences file or to specify individual preferences.
  • Have your users install an idl.pref file in the IDL_DIR/bin/bin.platform directory where platform is the platform-specific bin directory, and then launch the application by clicking on the SAVE file icon or by dragging it to the Virtual Machine icon.
  • Instruct your users to set environment variables that correspond to the preferences you need to specify.
  • If you are providing a runtime distribution for your application, you can install an idl.pref file in the IDL_DIR/bin/bin.platform directory yourself.

Options for UNIX/Mac Applications

If your Virtual Machine application runs under UNIX (including macOS), you have the following options:

  • Have your users launch the Virtual Machine application via the shell command line, and use the -pref command line option to specify a preferences file or to specify individual preferences.
  • Instruct your users to set environment variables that correspond to the preferences you need to specify.