[Info-vax] disabling a CTRL/Y ast

[Stephen Hoffman]

On 2016-01-06 16:46:32 +0000, Tom Adams said:

> I want to turn ctrl/y into a noop in certain regions of code and turn 
> ctrl/y into an exit in other regions of code.

Some background: I've posted more than a few replies here in the 
comp.os.vms newsgroup, specifically discussing the particular 
application in question and its general design, and an unfortunate 
aggregation of the UI and the more critical code paths, and your 
understandable preference to avoid restructuring the application code 
through reworking the existing design to block ^Y from arriving within 
the most critical sections of the code.

> I do find that it is necessary to run lib$disable_ctrl at the beginning 
> of the program and lib$enable_ctrl at the end of the program to restore 
> the previous CLI state, but I need to run asts to do the rest.

If you want ASTs in some parts of the code and not in others, then 
you're going to have to wrap those sections appropriately.   That's if 
you don't decide to migrate those critical code sections into another 
process context, or related steps.  Because beyond the potential for ^Y 
in these sections and the associated issues you're having with the 
image rundown processing in the absence of an EXIT command, other sorts 
of generic application failures ("bugs") or any arriving $forcex calls 
or such activities can potentially still leave the application in an 
indeterminate state.



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