Re: Procedure Examples VR7.1

Scott, one thing you might want to look at is my code at
www.think400.dk/downloads.htm. There are a series of projects that I wrote
and all of them are written using procedures and service programs.

If you look at them you will find service programs like:

1. Standard error handle, XVERRH.
2. User Space XVUSPC,
3. Temp Name XVTMPN.
4. Standard Message Functions XVMSGF
5. Resolve System object - XVRLSV
6. Dynamically Load a Service Program - XVDYNL


On Fri, Feb 3, 2017 at 9:40 AM, Charles Wilt <charles.wilt@xxxxxxxxx> wrote:

On Fri, Feb 3, 2017 at 9:54 AM, Duane Scott <dscott@xxxxxxxxxxx> wrote:

getting just the name or phone number of the main contact for that
customer record may not be necessary in but a few. Would a separate
procedure be written just to grab the contact from customer record?

​Is a few more than 1?

So the code required is reusable and rule #1
1. everything that can be reused, is an external procedure/function in an
service program

There's your answer.​ ;)

Consider the following scenario
You've got customer contact info in customer master table. You build a
CUSTOMER_GetContact().

Next year, it's decided that you need to have more than one contact per
customer. It's real easy to move the existing contact to a new
CUSTOMER_CONTACTS table and modify CUSTOMER_GetContact() to accept an
optional CONTACT_TYPE parameter. Without it, it returns the MAIN contact.
But you can also request CONTACT_TYPE = AP.

You don't have to modify or even recompile anything existing that uses
CUSTOMER_GetContact().

Honestly, code doesn't have to be re-used currently to be placed in a
service program. Placing it in a service program to start makes it
reusable in the future. Ideally all your business logic should be in a
service program.

Yeah, it's not going to happen overnight with an existing system. But when
adding enhancements (particularly around new tables) You should be thinking
about how to enable re-use of the new business logic. When modifying
existing logic, particularly logic that's been copied and pasted into
multiple places, take the time to figure out how to pull it out and into a
service program.

Take my new CUSTOMER_CONTRACTS table...I'd have at least
CUSTOMER_ListContacts()
CUSTOMER_CreateContact()
CUSTOMER_UpdateContact()
CUSTOMER_DeleteContact()

The logic to validate a contact (phone number, address, email, ect) would
be in an procedure internal to the CUSTOMER service program and called by
CUSTOMER_CreateContact() & CUSTOMER_UpdateContact().

An hey next year, when it's decided you need to allow the same contact info
to be used by multiple customers...it's lots easier to move the contact
info into a new CONTACTS table and the old CUSTOMER_CONTACTS becomes a
simple association table with just CUSTOMER_ID, CONTACT_ID, CONTACT_TYPE.

If you haven't seen one of Scott's presentations, take a look at this one.
http://www.scottklement.com/presentations/Pattern%20to%
20Good%20ILE%20with%20RPG.pdf

Charles
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