[Info-vax] Creating an open source version of VMS, was: Re: OpenVMS Hobbyist Notification

[Arne Vajhøj]

On 3/12/2020 4:28 PM, Dave Froble wrote:
> On 3/12/2020 1:27 PM, Stephen Hoffman wrote:
>> As for itemlists and descriptors. Good ideas ~40 years ago. Now, not so
>> much.
> 
> I'll see ya on that one, and raise.  Itemlists as implemented were NEVER 
> a good idea.  Way too much what Steve calls "glue code.  Maybe, just 
> maybe, they were the best option AVAILABLE at the time.  Start with 
> recalling the initial memory available on a VAX 11/780.

Descriptors was a good idea. And sort of still is. It is just
called object today.

What is a String in an OO language? A class (which via class id
tell what type of string it is) with a length and a char array
for content.

Itemlists are a bit weird. I assume they were introduced to
minimize the number of CALLS/CALLG executed (yes - it may have mattered,
I was once told that a VAX could spend 25% of time executing CALLS/CALLG
and RET). But today they are hard to work with.

> Ask why DEC provided the LIB$... and such routines.  It was to hide the 
> glue code from the customers.  Glue code isn't a bad thing.  It's what 
> makes OO type routines work.  It's better if it's not seen.
> 
> But it's there ....

LIB$ library is pretty small after todays standard. That is not
a problem.

In fact it should probably be significantly extended.

Arne