RE: [MI400] MI as the MI language of the as400.

["Steve Richter" <srichter@xxxxxxxxxxxxx>]

-----Original Message-----
From: mi400-admin@midrange.com [mailto:mi400-admin@midrange.com]On
Behalf Of Jim Langston

>As early as Visual Basic 3.0 (the one that ran under MS-DOS, not the
windows
>VBasic) we could do a lot of the same things we can do in ILE.  Visual
Basic
>3.0 would allow you to create a library, very similar to an RPG ILE
>Directory, with your functions and call them from your programs.  The
>library was in a separate object, .lib if I remember correctly.  ILE
reminds
>me quite a bit of this Visual Basic 3.0 and onward type of library
building,
>why it was rather easy for me to take ILE concepts and run with them.


I agree Jim.

All the buzzwords, all the rules, it all comes down to calling out of your
program and into a routine in an external module. DLLs, service programs,
COM servers, interfaces, programs.  They all are the same thing.

A DLL is similar to an ILE service program. When a VB program calls a
function in a DLL it has to first declare the function name, the dll it can
be found in, its name in the dll and its parameters.

like so:

Private Declare Function GetVersionEx Lib "kernel32" Alias "GetVersionExA"
(lpVersionInformation As OSVERSIONINFO) As Long

The VB program then calls the function just like a function that is coded
within the VB program.  At run time the DLL is located and loaded.

But that is old stuff. VB programmers for at least 4 years have had ActiveX
classes and controls. Behind the scenes these classes are coded in DLLs, but
the VB programmer just sees interfaces that are registered in the registery
and described in a type library object. The type library contains IDL (
interface defn language ) code that contains the Declare Function
information. So the VB programmer just has to select from a list of classes
and interfaces when calling out to the external functions ( actually class
methods ).

This aspect of VB combined with similar point and click features for
displaying information in a window makes VB a real good language.  Other
things a programmer has to do like print reports, deal with database files,
data structures and large program are not nearly as easy, and VB quickly
becomes cumbersome to work in.

Steve Richter