[Info-vax] Access to _all_ VMS system services and library functions from DCL ?

[Arne Vajhøj]

On 7/11/2017 10:11 PM, David Froble wrote:
> Simon Clubley wrote:
>> On 2017-07-10, David Froble <davef at tsoft-inc.com> wrote:
>>> Now, for data layout, if the data structure is included in VMS, and 
>>> "ALWAYS" used as-is, and no expectations are made on data size, then 
>>> after a fresh compile and link, you got the new sizes, and it's up to 
>>> you what you do with them.  VMS can make changes.  If they are 
>>> incompatible with your code, that's "your" problem.  Fix it.
>>
>> So in your way of doing things, every single program would have to
>> be recompiled after every single VMS upgrade before they could be used
>> in that new version of VMS. That's a rather "unique" way to handle
>> compatibility issues.

> The Codis system, which is rather large, can be re-built, on each 
> customer system, every night, if required.
> 
> It's just the way we approach things.  If you don't have sources, and if 
> you cannot re-build them, then you have an application that is doomed to 
> extinction.
> 
> I'm not saying that everything must be re-built after a VMS upgrade.  
> However, VSI must have the freedom to implement new features, and if 
> there is a need to use these new features, then yes, a simple re-build 
> is a cheap price to pay.

Other OS's usually allow programs to run unchanged after OS upgrades
(obviously there are exceptions for programs close to the OS let
us call it LINK/SYSEXE).

VMS not doing so would put it at a competitive disadvantage.

Last OS with an upgrade breaking everything I think was WP7->WP8. Guess
what - there will not be a WP9.

Arne