Resources

Centaur features a resource manager so that values for most system parameters (e.g., formalism locations, pretty printer colors and fonts, mouse event lists, etc.) may be specified by resources. These resources are stored in resource files that are read by Centaur into its resource database by necessity. Resources may be modified dynamically within a Centaur session.

A resource specification is a pair that assigns a value to a pattern. Each pattern represents the path leading to an object in the system hierarchy. The last word in the pattern is a property of the object for which we may furnish a value, such as the background color used by a pretty printer or the location of a formalism. Patterns are modeled after those used by the X window system.

Although resources are omnipresent in Centaur and any serious user must get to know them, we will avoid them as much as possible in this tutorial. We will explain them briefly when we examine pretty printer colors and fonts.

Resources are stored in a number of files that are read into the resources database as required. One file, named .centaur.rdb, should be created in your home directory. It is always read when you start up Centaur.

Another important file is the formalism resource file. This file specifies the location of the formalism definition, syntax and semantics information, and points to all other specification files for the formalism.

N.B.

• Any time you modify a resource specification in a file, you must click on the button in the Load pulldown of the main menu. This loads the resources, but does not inform tools of the new values. Typically, you will have to click on the button of a ctview's Display pulldown to take the resources into account.
• If ever resources don't do what you think they should, then verify the following:
  • You have not misspelled any words.
  • You may split a resources onto two lines by ending the first line with a backslash. Make sure that this backslash is not followed by blanks.
  • Make sure that the resource path you have specified is the right one, i.e., all the documented elements in the path are present and correct.
  • Make sure that your resource is the most specific one in the database (see the section on primitives in the resource manual of the Mantle).