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

[Simon Clubley]

On 2017-07-11, David Froble <davef at tsoft-inc.com> wrote:
> Simon Clubley wrote:
>> On 2017-07-10, David Froble <davef at tsoft-inc.com> wrote:
>>> Well, not just for DCL.  Have defined blocks of data for each system service. 
>>> Either I allocate the memory, (probably best) or have the system service 
>>> allocate the memory.  Then jam it full of all data provided by that system 
>>> service.  Sure would do away with item lists, at least to some extent.
>>>
>> 
>> 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.

>> 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.

Simon.

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