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

[Simon Clubley]

On 2017-07-12, David Froble <davef at tsoft-inc.com> wrote:
> Simon Clubley wrote:
>> On 2017-07-11, David Froble <davef at tsoft-inc.com> wrote:
>>> Simon Clubley wrote:
>>>>>
>>>> A single block of data which is directly accessed is too limiting and
>>>> will cause massive maintainence problems as structures are changed and
>>>> field sizes changed in the future.
>>> Why?
>>>
>> 
>> Because existing binaries will now be looking at the wrong locations
>> for the data items they need.
>
> Not if the system service rejects an improper data block.
>

Erm, in your scheme, it's the _output_ from the system service which
will have changed format, not the input.

>>>> This will lead to a different version of the data block for every
>>>> change in the future and all these versions would have to be kept
>>>> around in the future as well as the code to populate them.
>>> Why?
>>>
>> 
>> Because it is expected that you are able to run existing user mode
>> applications unchanged on the upcoming versions of an operating system.
>
> Only if you worship at the 100% compatibility alter.  Which as Steve has 
> mentioned, stifles new capabilities.  Face it, if you want to be able to 
> improve, then sometimes there is a price to be paid.  If you don't want 
> improvements, run your current version of the OS forever.

This scheme instead would be pretty close to 0% upwards compatibility.

Your scheme would break compatibility on every minor change to the
data structure, not just the major changes.

$ set response/mode=good_natured

Since I refuse to believe you can't see that, I am going to assume
instead that you are just trolling for responses. :-)

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
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