Understanding global blocks
Global symbols can be defined with the GLOBALS
instruction
The GLOBALS
instruction can be used to declare variables, constants and types
for the whole program.
Defining global variables in a GLOBALS
block is deprecated. Instead of
GLOBALS
, use PUBLIC
symbols in modules to be imported with IMPORT FGL
. GLOBALS
is
only supported for backward compatibility, to compile legacy source code.
Why not globals? Global variables visible and modifiable across the entire program code is an old
concept that reduces modularity and flexibility. GLOBALS
implements specific
semantics that restrain source code organization; for example, it is allowed to specify a file path
such as GLOBALS "../../common/myglobals.4gl"
. The globals file can define functions
after the GLOBALS
block that are ignored when including such file.
Conversely, the IMPORT FGL
instruction brings more flexibility and allows a
better organization of your source code, by grouping public variables in modules where other symbols
(functions, types, contants) belong to the same domain.