$Id: clipper.txt,v 1.3 2001/08/07 23:20:56 ronpinkas Exp $

This document attempts to describe the features separating Harbour from
Clipper.

/* TODO: @FunPointer(), and all other Harbour extensions. */

Harbour Macro Compiler
----------------------
The Harbour Macro Compiler offers 2 additional layers of functionality
controlled by means of HB_SETMACRO()* function, not available in Clipper.

HB_SETMACRO( HB_SM_HARBOUR, TRUE ) will enable macro compilation and
evaluation of complex expressions not supported by Clipper like:

 - exp++, exp--, var += exp, (exp), etc..
 - Nested codeblocks.
 - Expressions longer then 254 characters.

HB_SETMACRO( HB_SM_XBASE, TRUE ) will enable macro compilation and
evaluation of comma separated lists in all contexts where lists are
acceptable by Clipper*, including:

  - { &cMacro } // Literal array elements list.
  - SomeArray[ &cMacro ] // Array index list.
  - SomeFun( &cMacro ) // Arguments list.
  - ( &cMacro ) // parenthesized list expression.

*Clipper only supports list macros within codeblocks context.

Both these extra layers are activated by default.

* See also -k Compiler switch.

LIST Command
------------

LIST &cMacro

LIST in clipper [superficially] supports macros of lists expressions.
No error will be produced, and all expressions in the list will be
evaluated, but *only* the *last* expression will be displayed. This is
not documented in either the LIST Command or the Macro Operator
descriptions, but is the de-facto behavior in all Clipper 5.x versions.

Harbour instead will not only evaluate all of the expressions in
such list macro, but will also display all such values. This default
behavior may be disabled with HB_SETMACRO( HB_SM_XBASE, .F. )*

* See also -k Compiler switch.

INIT/EXIT and startup procedures
--------------------------------

In Clipper the startup procedure is always the first procedure/function
of the main module, even if such symbol is an INIT or EXIT symbol. In
such case the program will never execute the "main" symbol. In Harbour
the first *non* INIT/EXIT symbol, will be executed as the main symbol
after all INIT procedures have been executed.

