Libraries

Programs having the Library program type are not compiled when you select All or Changed programs in the Program Compiler. They are simply collections of procedures and are not executable. The arrangement of the procedures within a library program has no significance.

A Library program is useful if you want to do any of the following:

• Start with the lowest-level procedures and construct your program using a bottom upwards method
  
• Keep all similar procedures together for ease of editing or to help you to identify suitable procedures or bodies for use elsewhere
  
• Overcome or avoid the error Too many procedures in program. This error is encountered long before the program is too big to compile. By putting some procedures into a library and tying them there, you reduce the number of procedures that are simultaneously available for editing. The tied procedures are edited from within their library
  
• Merge an overlay into the main program. Change the overlay program to type Library leaving it otherwise unchanged, because it will now be unnecessary to compile it separately
  
• Tie the procedures "owned" by a particular member of a development team to warn other members not to edit these procedures. You cannot prevent them from doing so, but tying will minimise the risk of accidental changes
  

It is helpful to decide on some naming conventions before writing any programs, especially if the application could eventually be a large one. It is very difficult to locate a particular procedure or body in the list unless you know approximately where it must appear.

A 2 or 3 letter prefix can act as a reference to a particular library, so that you can quickly find where to view or edit a procedure.