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

[Simon Clubley]

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.

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.

There is a strong argument for an easier than currently exists method
to get at this data, but there still needs to be some level of abstraction
in order to be able to handle these issues.

Oh, and for something like this, if it was done anyway, there's no way
you should pass in the memory to be used. For a structure this complex,
VMS would need to control the memory it was writing to for safety reasons
and that means it allocates the memory and returns a pointer to it.

> If I can "include" the data structure in my programs, and then reference the 
> data by name, sure would make things simpler.

And what about when the data block is changed because a field is
expanded (for example) ?

Simon.

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