Description: Pascal II: Using Library Name Files
Header: Pascal II: Using Library Name Files

 Many people have trouble using Library Name Files in Apple II Pascal
 (v.1.2 and 1.3 ). Here is a short explanation on what library name
 files are, and how they are used in Pascal.

 Library Name files, which contain the names of libraries to be used when
 running a program, are designed for very large applications, or for
 multiple program applications that need to use the same libraries.

 With small applications, when you want to use a library other than the
 system library, you can link your libraries ( as regular units )
 directly into your program. For larger applications, however, this is
 impracticable, since each re-compilation makes linking more difficult
 and cumbersome.  The solution for larger applications is to create
 Program Libraries which allow you to build your own set of intrinsic
 units without having to place them in the system library. (Intrinsic
 units have the same root name as the program, but have the suffix '.LIB'
 on the end; e.g., a program  named TRYIT.CODE becomes TRYIT.LIB).  What
 Library Name files do is allow you to handle up to five Program Library
 files for each program.

 To use Library Name files, write your library code and program code in
 the standard way. Each library unit MUST be an intrinsic unit. When
 writing your program you must remember to use the "$U ..." option to
 tell the compiler where to find your libraries interface (program
 library names are used only at execution time.). After compiling your
 library units, don't forget to use the LIBRARY program to place a
 library header in the file. Now, just compile your program and create
 your library name file. When you execute, your program will find its
 units even though you did not have to link them in.

 Here are three sample files that illustrate the process:


 Main program source code [TRYIT.TEXT]:

 PROGRAM USEWALLY;

 USES    {$U WALLY.LIB} WALLY;

 BEGIN
    DOWALLY;
 END.



 Wally, library unit source code [WALLY.TEXT]:



 UNIT WALLY;

 INTRINSIC CODE 17 DATA 18

 INTERFACE

 VAR    WALLSTR:STRING[80];

 PROCEDURE DOWALLY;

 IMPLEMENTATION

 PROCEDURE DOWALLY;

 BEGIN
    WRITELN('WELL WALLY WORKS WELL I THINK');
 END;



 BEGIN

 END.



 Library name file [TRYIT.LIB]:



 LIBRARY FILES:

 WALLY.LIB

 $$



 To build this program, you must compile the library unit first, then use
 LIBRARY to turn it into a library (with the proper header). Finally,
 compile the main program ( TRYIT.TEXT) and then run it to be sure that
 it works.



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