[TUHS] origins of void*

[Warner Losh]

On Mon, Nov 6, 2017 at 12:24 AM, <arnold at skeeve.com> wrote:

> Paul Ruizendaal <pnr at planet.nl> wrote:
>
> > >> In the 4BSD era there was caddr_t, which I think was used for pretty
> > >> much the same purposes.
> > >
> > > Only for kernel code. I am pretty sure caddr_t wasn't used in
> user-land code.
> >
> > Ah, thanks for pointing that out, I had not realised that and it helps
> > explain some things. But why wasn’t caddr_t used for user-land code:
> > usage in the signature of e.g. write() would have made sense, right?
>
> It's clear from K&R 1 that char* served as both pointer to string and
> generic pointer to memory.  That's not unreasonable, since, in some sense,
> "memory is just bytes".  So user-land code didn't need caddr_t.  I also
> suspect that caddr_t came into being with the effort to port Unix off
> the PDP-11 and the weight of Unix practice before then had been to make
> do with char*.
>
> I think it helps to remember the evolutionary processes that were happening
> in the '70s.  High level languages had caught on for application code
> (FORTRAN and COBOL in the US, Algol in Europe) but the weight of existing
> practice for *systems coding* (operating systems and utilities) had been
> to use assembly language.  Multics proved that you could write an OS in
> a high level language, but Multics itself (at that time) wasn't a success.
>
> So when C came along in the mid-'70s, strong typing had essentially been
> absent from systems programming.  With time and experience, along with
> the recognition in the general CS world that strong typing was valuable,
> C also started to evolve in that direction.
>

I thought there'd also been some influences from BLISS... DEC did much of
their system programming in BLISS along side the MACRO-{11,32,20}....  Not
exactly a strongly typed language, but another entry in the higher level
language category that C was competing against.

Warner
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