Jerry Stuckle wrote:
On 10/17/2013 10:32 PM, Miles Fidelman wrote:
berenger.mo...@neutralite.org wrote:
So, what you name an OS is only drivers+kernel? If so, then ok. But
some people consider that it includes various other tools which does
not require hardware accesses. I spoke about graphical applications,
and you disagree. Matter of opinion, or maybe I did not used the
good ones, I do not know.
So, what about dpkg in debian? Is it a part of the OS? Is not it a
ring 3 program? As for tar or shell?
Boy do you like to raise issues that go into semantic grey areas :-)
Not specially, but, to say that C has been made to build OSes only,
you then have to determine what is an OS to make the previous
statement useful. For that, I simply searched 3 different sources on
the web, and all of them said that simple applications are part of the
OS. Applications like file browsers and terminal emulators.
Without using the same words for the same concepts, we can never
understand the other :)
I'm pretty sure that C was NOT written to build operating systems -
though it's been used for that (notably Unix).
Yes, it was. It was developed in the late 60's and early 70's at
AT&T's Bell Labs specifically to create Unix.
To quote from the first sentence of the Preface to the classic C book,
"The C Programming Language" by Kernighan and Ritchie, published by Bell
Labs in 1978 (pretty authoritative given that Ritchie was one of C's
authors):
"C is a general-purpose programming language ...."
Yes, the book came out around 1978 - several years AFTER C was
initially developed (and used to create Unix), and after people had
started to use C for applications programs.
Good point. After reading your email, I did a little more digging, and
found a wonderful conference paper - also by Dennis Ritchie - talking
about the origins and development of C in gorry detail. A pretty
definitive source (given that he wrote C), and a good read:
http://cm.bell-labs.com/who/dmr/chist.html
It wasn't exactly written "specifically to create Unix" - to quote
Ritchie "C came into being in the years 1969-1973, in parallel with the
early development of the Unix operating system; the most creative period
occurred during 1972."
It was, however, developed in reaction to shortcomings in the languages
used to create the earliest versions of Unix (PDP-7 assembler, and then
B - insprired by BCPL).
Now there ARE "systems programming" languages that were created for the
specific purpose of writing operating systems, compilers, and other
systems software. BCPL comes to mind. PL360 and PL/S come to mind from
the IBM world. As I recall, Burroughs used ALGOL to build operating
systems, and Multics used PL/1.
I don't remember an OS built on ALGOL. That must have been an
experience? :) I didn't use PL360, but PL/S was basically a subset of
PL/1 with inline assembler capabilities. It was nice in that it took
care of some of the "grunt work" (like do and while loops and if
statements).
I THINK Burroughs used Algol as a systems programming language. But
it's been a long time.
<snip>
I'd simply make the observation that most SQL queries are generated on
the fly, by code - so the notion of building SQL requests to "experts"
is a non-starter. Someone has to write the code that in turn generates
SQL requests.
Not in my experience. I've found far more SQL statements are coded
into the program, with variables or bind parameters for data which
changes.
Think about it - the code following a SELECT statement has to know
what the SELECT statement returned. It wouldn't make a lot of sense
to change the tables, columns, etc. being used.
And in some RDBMS's (i.e. DB2), the static SQL statements are parsed
and stored in the database by a preprocessor, eliminating significant
overhead during execution time.
I've seen a lot of utilities for browsing databases - that basically
build SELECT statements for you. I expect that this only gets more
complicated in building data mining applications.
--
In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra
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