[Info-vax] DCL's flaws (both scripting and UI)

[Stephen Hoffman]

On 2015-01-22 03:48:35 +0000, Bob Gezelter said:

> Breaking existing behaviors is a non-starter. Even if you ask customers.

Breaking existing behavior can be exactly the right thing to do for 
some cases of broken software, but it's not the right thing to do in 
the case of DCL.

DCL is a workable mess for its present use, and there's too much 
existing DCL around to nuke it outright, and DCL works well enough that 
there's justification possible for nuking it outright.

Best to get a plan and a design for a much better replacement, and then 
get that much better replacement online and working and in the field, 
and after (many) years and (probably) after (reliable) automatic 
translation, and on a schedule, then nuke DCL from orbit.  That 
replacement might have wholly new syntax and the ability to execute 
existing DCL, or it might be entirely different with some form of 
translation that (for instance) activates when it sees "$" command 
prefixes in command procedures.

Again, there needs to be a replacement design, and that design needs to 
either be compatible with the current DCL environment — which won't be 
easy, here — or there needs to be a feasible migration path.  Given how 
many one-shot DCL commands are embedded into applications and issued 
via SPAWN, replacing DCL wholesale will be very difficult, and those 
customers that are going to actually upgrade are going to want a 
migration path and/or a good replacement.

But I just don't see any of this happening anytime soon, as VSI has 
much bigger problems to address, and many problems that are much more 
isolated than would be extending or replacing DCL.   I'd expect to 
(eventually) see some nibbling around the edges of DCL from VSI folks, 
but truly overhauling DCL is not going to be easy within the 
constraints of the current DCL design[1], and there some fixes and some 
enhancements that would be particularly difficult[2], as any overhaul 
and any wholesale replacement will slam headlong into over thirty years 
of accumulated, knotty and sometimes sketchy DCL code.



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[1] I'm not at all sure there actually is a design for DCL around; just 
some documentation and a reference model.
[2] such as removing the asymmetric quoting, or reworking the 
quoted-quoting, or adding transparent UTF-8 support.


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Pure Personal Opinion | HoffmanLabs LLC