Identifying modules to be imported

Use the --print-missing-imports and --print-imports options to identify missing IMPORT FGL instructions.

When migrating existing projects using traditional linking, after compiling all the .4gl sources, consider using the --print-missing-imports option of fgllink or fglrun, to print the IMPORT FGL suggestions for all the modules specified in the fglrun command line.

On the other hand, the --print-imports option reports all imported modules that are really used.

Just add the --print-missing-imports to the fgllink or fglrun -l commands, to identify what modules should be imported:

$ head *.4gl
==> main.4gl <==
MAIN
    CALL func1()
END MAIN

==> mod1.4gl <==
FUNCTION func1()
    CALL func2()
END FUNCTION

==> mod2.4gl <==
FUNCTION func2()
END FUNCTION

$ fglcomp *.4gl

$ fgllink --print-missing-imports -o prog.42r *.42m
-- in main.4gl
IMPORT FGL mod1

-- in mod1.4gl
IMPORT FGL mod2

The --print-missing-imports option will try to resolve all (function) symbols as done during linking, but instead of producing a .42r program, it will list the IMPORT FGL instructions to be added in each module, and thus avoid linking.

The --print-imports option prints all IMPORT FGL instructions, that are really used by a module, where at least one symbol (function, variable, constant, type, etc) is used by the importing module.

Consider using the --print-missing-imports options instead of --print-imports: If you are missing an IMPORT FGL for a non-function symbol like a variable, constant, or type, the compiler will produce a compilation error. Regarding function symbols, the compilation is possible even when the module was not imported. Therefore, --print-missing-imports is useful to identify modules to be imported to resolve function symbols and avoid linking.

In the next example, mod1 can be imported in main, but mod2 already imports mod1:

$ head *.4gl
==> main.4gl <==
MAIN
    CALL func1()
END MAIN

==> mod1.4gl <==
FUNCTION func1()
   CALL func2()
END FUNCTION

==> mod2.4gl <==
IMPORT FGL mod1
FUNCTION func2()
   CALL func1()
END FUNCTION

$ fglcomp main.4gl mod1.4gl mod2.4gl

$ fglrun --print-imports main.42m mod1.42m mod2.42m
-- in main.4gl
IMPORT FGL mod1

-- in mod1.4gl
IMPORT FGL mod2

-- in mod2.4gl
IMPORT FGL mod1

$ fglrun --print-missing-imports main.42m mod1.42m mod2.42m
-- in main.4gl
IMPORT FGL mod1

-- in mod1.4gl
IMPORT FGL mod2