[Info-vax] "Clever code", was: Re: wrong file format

[Simon Clubley]

On 2021-01-08, Stephen Hoffman <seaohveh at hoffmanlabs.invalid> wrote:
> On 2021-01-08 13:14:12 +0000, Simon Clubley said:
>
>> Yes. The VMS terminal driver is an example of this idiotic mindset and 
>> is also the reason why, in 2021, we can't even do something as simple 
>> as edit DCL command lines which are longer than the terminal width. :-(
>
> Pragmatically, the terminal driver class-and-port design has survived 
> for an unusually long time for software, and is still in active use.
>

Is that because everyone is afraid to go near it ? :-)

> Terminals and storage I/O are the two biggest class-and-port driver 
> stacks, and for similar reasons?trying to have logic common to all 
> devices, without having to maintain and update common code across 
> multiple monolithic device drivers; splitting device-generic from 
> device-specific processing.
>
> The design assumptions and trade-offs around the terminal driver and 
> LOGINOUT and JOB_CONTROL and CLI are all inter-related, too. Might 
> command editing be better implemented in the CLI? Quite possibly. 
> Probably. Sure. But there are requirements around responsiveness, and 
> moving editing further from the hardware usually adds latency. In years 
> past, terminal hardware was really slow. And some was even slower. So 
> too was VAX slow. And debugging a CLI gets... interesting, too.
>
> For why this line-editing length limit still exists? Not clever nor 
> idiotic code. I'd tie that limit to a ~thirty year old class-and-port 
> driver design mixed with support for yet older hardware and sorta-kinda 
> support for far newer software terminals, with a very large dollop of 
> compatibility-preservation, along with fewer non-revenue-focused 
> long-term investments than any of us including the folks in OpenVMS 
> development might prefer. Forever-compatibility has its costs. And 
> rip-and-replace is less than popular with the apps and users dependent 
> on the existing behavior. (There was some other and non-technical "fun" 
> arising here aeons ago, too.)
>

There might have been somewhat valid reasons for the design at the time,
but when it was implemented in a way that makes people afraid to go near
it, then that does sound like "clever" coding to me.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.