Extending or Replacing the Help System

The data entry and menu help function, kd_help(), and the choice list help function, kc_help(), initialize two help structures, one for the first-level of help and one for the second-level of help. How these help structures are initialized depends on the current position of the cursor. The only exception is when kc_help() is called from within a stand-alone choice list; in this case, only one level of help is initialized. After the help structure or structures are initialized, the system help function, help_proc(), is called.

help_proc() examines the first-level help structure and determines if there is a string or section of the memory file that can be displayed. If there is, help_proc() pops up the help window and displays the information. Control is passed to the user for browsing through the help information. Keyboard processing is done using the help event table. If the user presses the Help key again, the second help structure is examined and the help information, if any, is displayed.

The help system can be extended or replaced in the following ways:

• nAdding additional processing to the help function. You can do additional processing before the help function is called or after it returns. For example, you may want to conditionally change the help memory file or call mf_rd() to read the help file into memory.
  
  
• nCalling the system help function, help_proc(), directly. You can write a help event function that initializes the help structures and then calls help_proc(). In this way, you can add more levels of help than the two levels provided by the system, or you can attach help to windows or other objects.
  
  
• nImplementing your own help system. You can replace the entire help system with one that you have developed. For instance, you may want to develop a help system containing a menu of help topics or help tutorials.