[Info-vax] Greg Kroah-Hartman on backwards compatibility

[Stephen Hoffman]

On 2020-12-01 15:11:58 +0000, geze... at rlgsc.com said:

> I do not disagree that the mechanics of QIO are dated. However, 
> focusing on the mechanics of itemlists, etc. is missing the primary 
> point of my comment. Syntax changes are indeed vexing, but they are 
> just that, syntax.

I find $qio archaic and itemlists archaic, and the stability of $qio 
arguably has as much to do with the longstanding allergy to even making 
any changes as with any API stability or its (in)elegance.

And it's all syntax sugar, all the way down to the machine code. A 
Simple Matter Of Programming. Of development by first principles. Of 
the wars among those working with compilers and those using assemblers, 
in decades past. But I digress.

> When I referred to QIO, I was referring to the semantic definition.

Add an obscure literary reference or a TikTok link, and my bafflement 
and befuddlement would be complete.

> Generally speaking, syntax issues are local. Semantic changes are far 
> more global and have a larger impact. IMO.

Or as I put it, fixing $qio and tweaking the design limits piecemeal 
got us into this mess (e.g. 64-bit APIs, etc), and OO is one potential 
fix.

I've previously commented that Microsoft .NET looks like the OpenVMS 
calling standard, a couple of decades on.

Though OO is not a small effort for VSI and for existing tooling and 
for existing and future developers, and an effort where acceptance can 
and would only be measured in decades.

As lauded and sought after as endemic and perpetual compatibility might 
be, and as necessary as compatibility is for everybody particularly 
short-to-mid-term, endemic upward compatibility is fundamentally 
disastrous for the vendor long-term, and is more subtly problematic  
for the end-users longer-term.

Our ability to predict the appropriate hardware and software trade-offs 
a decade or two out is poor. And more recently we've been operating 
with retrofit fixes for VAX-era 16- and 32-bit designs for a couple of 
decades. Which is where that and similar articles get into trouble. 
Sooner or later, every environment collapses under the weight of its 
compromises, whether semantic or syntax or API or otherwise. Or it 
changes.


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