OVERLAY.DOC
===========

{               Copyright 1990 TechnoJock Software, Inc.               }
{                          All Rights Reserved                         }
{                         Restricted by License                        }

{                    Credits: Rob Rosenberger - thanks!                }

INTRODUCTION
============
One day, Rob Rosenberg called and informed us that our Overlay section
in chapter three was factually incorrect! Worst still, he was right

The bottom line is "overlaid units may have an initialization section".
The only requirement is that the overlay manager must be initialized 
first so it can load and execute the overlaid units.

The Toolkit includes a small unit TOTOVR.PAS which is designed as a 
template unit for initializing the overlay manager. Each time you need to
overlay some Toolkit units, you should make a copy of TOTOVR.PAS
to a new file, e.g. AccntOVR.PAS. Then edit the name of the program overlay
file (default: program.OVR) to reflect the name of the file which will 
contain the compiled overlay code, e.g. ACCOUNTS.OVR.

The USES statement of the main program must list the AccntOVR file (or 
whatever name you gave the unit) before the Toolkit units which are to be
overlayed. For example:

program AccountsPayable;
{ACCOUNTS.PAS}
{$F+}
USES OVERLAY,DOS,CRT,
     AccntOVR, totFAST, totWIN, totIO1;

{$O totFAST}
{$O totWIN}
{$O totIO1}

begin
   {.....}
end.


In the example, by the time the programs tries to load totFAST, the overlay
manager has already been installed (by AccntOVR) and so the totFAST 
initialization unit can be successfully executed as an overlay.

A new Compiler Directive OVERLAYINIT can be used with the Toolkit. If
OVERLAYINIT is used in preference to OVERLAY, the Toolkit units will be
compiled in an overlayable state, and the individual unit initialization
sections *will* be executed, i.e. you will not need to call the  unitINIT
procedures as described on page 3-8 of the manual.

A new example, DEMOVR3.PAS illustrates the use of this new compiler directive.

The use of the OVERLAY unit as described in the User's Manual (page 3-8) is
still functional, and may be appropriate in some circumstances. 

UNIT DEPENDANCIES
=================

This section details the Toolkit unit dependancies. In other words, the units
used by each Toolkit unit. This information is important when you want to
overlay Toolkit units using the OVERLAY compiler directive.

If you enable the OVERLAY compiler directive in the TOTFLAGS.INC file, you
must manually call the initialization procedure for each unit. Every Toolkit
unit has an initialization procedure, and this procedure name is consistently
the unit name minus the TOT prefix plus the characters "INIT". For example,
the initialization procedures for the TOTFAST and TOTSYS units are FASTINIT
and SYSINIT, respectively.

Listed below are the unit dependancies:

totSYS   - none

totLOOK  - totSYS

totREAL  - none

totINPUT - none

totFAST  - totSYS, totLOOK, totINPUT

totWIN   - totSYS, totLOOK, totINPUT, totFAST, totSTR, totMISC

totMSG   - totSYS, totLOOK, totINPUT, totFAST, totMISC, totWIN, totSTR,
           totIO1, totREAL

totLINK  - totREAL, totINPUT, totSTR

totLIST  - totSYS, totLOOK, totINPUT, totFAST, totMISC, totWIN, totSTR,
           totREAL, totIO1, totLINK

totDIR   - totSYS, totLOOK, totINPUT, totFAST, totMISC, totWIN, totSTR,
           totIO1, totREAL, totLINK, totDATE, totMSG, totIO2

totIO1   - totSYS, totLOOK, totINPUT, totFAST, totMISC, totWIN, totSTR,
           totREAL

totIO2   - totSYS, totLOOK, totINPUT, totFAST, totMISC, totWIN, totSTR,
           totIO1, totREAL, totLINK, totDATE, totMSG

totIO3   - totSYS, totLOOK, totINPUT, totFAST, totMISC, totWIN, totSTR,
           totIO1, totREAL, totLINK, totDATE, totMSG, totIO2

totMENU  - totSYS, totLOOK, totINPUT, totFAST, totMISC, totWIN, totSTR,
           totIO1, totREAL, totLINK

totSTR   - totREAL, totINPUT

totDATE  - totSYS, totREAL, totINPUT, totLOOK, totSTR

totMISC  - totFAST, totSTR