Exception Handling

Exception Handling

[Robbie Gates]

Hi all,
  Just a quick query:
Where did the concept of exception handling originate ? For example,
which languages were first to support this, or which papers first
proposed exception handling ?
  replies by email please, i don't read this group.
- robbie
-- 
----------------------------------------------------------------------
      robbie gates      |
  apprentice algebraist |    http://cat.maths.usyd.edu.au/~robbie
    pgp key available   |

Re: Exception Handling

[Patrick Doyle]

In article <323750EA.167E@maths.usyd.edu.au>,
Robbie Gates  <robbie@maths.usyd.edu.au> wrote:
>Hi all,
>  Just a quick query:
>Where did the concept of exception handling originate ? For example,
>which languages were first to support this, or which papers first
>proposed exception handling ?
>  replies by email please, i don't read this group.
>- robbie

  Ha ha ha!

  Well, if you're not going to bother reading this, I won't bother 
writing it.

 -PD

Re: Exception Handling

[Bryce]

-----BEGIN PGP SIGNED MESSAGE-----

 Robbie Gates  <robbie@maths.usyd.edu.au> wrote:
>Hi all,
>  Just a quick query:
>Where did the concept of exception handling originate ? For example,
>which languages were first to support this, or which papers first
>proposed exception handling ?
>  replies by email please, i don't read this group.


Hm.  University must be in session again.  Are there any other
homework questions you would like me to answer while I'm at it?


:^)


Bryce

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Re: Exception Handling

[Rick Decker]

Patrick Doyle wrote:
> 
> In article <323750EA.167E@maths.usyd.edu.au>,
> Robbie Gates  <robbie@maths.usyd.edu.au> wrote:
> >Hi all,
> >  Just a quick query:
> >Where did the concept of exception handling originate ? For example,
> >which languages were first to support this, or which papers first
> >proposed exception handling ?
> >  replies by email please, i don't read this group.
> >- robbie
> 
>   Ha ha ha!
> 
>   Well, if you're not going to bother reading this, I won't bother
> writing it.
> 
>  -PD

Robbie,

Perhaps a more felicitous wording might have been "please reply by
email if you don't want to clutter up your group with replies
to my query."  Although opinions differ, it's usually considered
polite when you ask a question of a newsgroup to lurk around for
a few days to see what answers you get.  Though most newsreaders
give the option of an email response, that feature doesn't exist
(or doesn't work) on all, so asking for an email response requires
extra work for some people.

BTW, PL/I is usually credited for first using exceptions, though
rudimentary forms existed as far back as COBOL.

Regards,

Rick

-----------------------------------------------------
Rick Decker                   rdecker@hamilton.edu
Department of Comp. Sci.      315-859-4785
Hamilton College
Clinton, NY  13323            =  !=  ==  (!)
-----------------------------------------------------

Re: Exception Handling

[Larry Kilgallen]

In article <519bl1$bta@lace.colorado.edu>, wilcoxb@cs.colorado.edu (Bryce) writes:

>  Robbie Gates  <robbie@maths.usyd.edu.au> wrote:

>>Where did the concept of exception handling originate ? For example,
>>which languages were first to support this, or which papers first
>>proposed exception handling ?
>>  replies by email please, i don't read this group.

With 5 newsgroups getting the post, I can see why not.

> Hm.  University must be in session again.  Are there any other
> homework questions you would like me to answer while I'm at it?

Bryce, the fact that you would be doing somebody's homework for
them should certainly not deter you from providing answers.

The rest of us will understand, however, if you choose not to
provide _correct_ answers :-)

Larry Kilgallen

Re: Exception Handling

[Robbie Gates]

Firstly, an open apology to the people annoyed by my post.  I realise
now it was unecessarily terse, but it didn't seem like a complex
question
nor one needing long discussion.  live & learn.

I (robbie@maths.usyd.edu.au) wrote:
> >>Where did the concept of exception handling originate ? For example,
> >>which languages were first to support this, or which papers first
> >>proposed exception handling ?
> >>  replies by email please, i don't read this group.

Larry Kilgallen wrote:
> With 5 newsgroups getting the post, I can see why not.
Another reason i wanted replies by email, to avoid this sort of
crossposting.  I'm only crossposting this so i can say sorry to
those i've incovenienced.  I do read one of the groups (evidently),
i didn't want to have to track 5 groups for what should have been
an easy answer.

wilcoxb@cs.colorado.edu (Bryce) writes:
> > Hm.  University must be in session again.  Are there any other
> > homework questions you would like me to answer while I'm at it?
Larry Kilgallen wrote:
> Bryce, the fact that you would be doing somebody's homework for
> them should certainly not deter you from providing answers.

For the record, it's not homework, i should have explained more fully.
I'm a pure math phd student, and part of my work provides a nice
model of some parts of programming, in particular exception handling.
i'd like to give proper credit to the originator of the concept, and
will of course acknowledge my sources and the people who helped me
find them.

none of my C++ or Java books actually said where the idea came
from, and so i figured it wasn't common practice in books on programming
to actually say where features originated.  Hence a library search
seemed
pointless with some information to narrow it, hence my post.
judging from my difficulty in finding the answer in places i expected
to find it, a post to several newsgroups on languages i do know support
exception handling didn't seem overkill.

> The rest of us will understand, however, if you choose not to
> provide _correct_ answers :-)
i don't know about you, but i would hardly believe anything i read
on usenet unless i could independently verify the referenced sources.

'nuff said, i'm sorry & i hope y'all understand my position a little
better now.

- robbie

-- 
----------------------------------------------------------------------
      robbie gates      |
  apprentice algebraist |    http://cat.maths.usyd.edu.au/~robbie
    pgp key available   |

Re: Exception Handling

[Felix Kasza]

Robbie,

 > replies by email please, i don't read this group.

Not feeling very sociable today, are we?

 > Where did the concept of exception handling originate ?

I don't know -- but I do know that IBM's /360 architecture uses a
mechanism for OS calls which looks very much like a trap.  PDPs used
similar features to handle illegal memory references.  In the late 60s
or early 70s, I saw an APL interpreter for the PDP that expressly made
use of this although it didn't export the functionality to the
programmer (APL has no concept of an exception).

Cheers,
Felix.

Re: Exception Handling

[Larry Kilgallen]

In article <323855BA.5246@hamilton.edu>, Rick Decker <rdecker@hamilton.edu> writes:

> BTW, PL/I is usually credited for first using exceptions, though
> rudimentary forms existed as far back as COBOL.

When the VAX came out in 1978, it had exceptions built into the
instruction set, and handling them had to be built into the
languages (even if in a clunky fashion).

Before there were Bliss-32 and Bliss-16 with comprehensive
exception handling, there were Bliss-36 and Bliss-11 which
may or may not have had support for exception handling.
I was under the impression that Bliss was originated at
Carnegie Mellon University by the person who went on to
found Tartan Labs.

Presuming application-specific stack-based handling of exceptions
was not a new concept introduced with the VAX, one might want to
follow the hardware trail back to see what non-standard language
support was provided. I don't think the original request nor the
clarification of purpose said anything about the support being in
standardized languages, and in fact that would seem to be the
opposite of giving credit to the true originators.

Larry Kilgallen

Re: Exception Handling

[David B. Shapcott [C]]

In article <32393072.72033128@shdgate.shd.de>,
Felix Kasza <felixk@mailbag.shd.de> wrote:
>Robbie,
>
> > replies by email please, i don't read this group.
>
>Not feeling very sociable today, are we?
>
> > Where did the concept of exception handling originate ?
>
>I don't know -- but I do know that IBM's /360 architecture uses a
>mechanism for OS calls which looks very much like a trap.  PDPs used
>similar features to handle illegal memory references.  In the late 60s
>or early 70s, I saw an APL interpreter for the PDP that expressly made
>use of this although it didn't export the functionality to the
>programmer (APL has no concept of an exception).

I've heard that the Babbage Engine had an ingenious exception mechanism
consisting of a cog and spring-loaded trip mechanism, that would activate
a rod releasing a steel ball-brearing down a raceway.  The weight of the
ball bearing was the value of the exception being thrown (for some time,
Babbage had actually considered a throwing arm mechanism, but found that
his mechanism could not be made accurate -- but this does provide an
interesting historical account for the phrase `throwing an exception').


-- 
D. Brad Shapcott [C]
Contractor, Motorola Cellular Infrastructure Group

Re: Exception Handling

[Paul A. Houle]

Don't sweat it.  People on newsgroups treat each other like
garbage.  This is because we can.  If people talked trash to each
other the way that we do on USENET,  we'd see visual nonverbal
signals of agression that would make us feel to distressed to
continue.

	When the people on the other end of the connection are
nothing more than a bit of badly written,  and these days,  badly
formatted,  text sometimes you get to feel that people should get
the death penalty for stupid posts,  unsolicited commerical spam
and such.

	Another issue is that computer people are not good about
attribution.  To take an example,  it seems clear that the advances
in compiler technology from,  say,  the mid 60's to the mid 80's
sprang from the lingustic discoveries of Noam Chomsky.  Most of the
people who use the technology don't care.  In fact,  even CS
academics don't talk about it much,  probably because they
associate Noam Chomsky with the student protests of the 1960's
and opposition to the Vietnam war.  

	I get the impression that people learn programming from
copying other people's code.  If book publishers were honest about
it,  they'd write a book titled "Learn to Cut and Paste Java in
21 Hours!"  People are more concerned with getting a program
working fast than they are on attributing the source.

Re: Exception Handling

[Norman H. Cohen]

In article <323750EA.167E@maths.usyd.edu.au>, Robbie Gates
<robbie@maths.usyd.edu.au> writes: 

|> Where did the concept of exception handling originate ? For example,
|> which languages were first to support this, or which papers first
|> proposed exception handling ?

A good early survey of exception handling can be found in: 

   Goodenough, John B.  Exception handling:  issues and a proposed
   notation.   Communications of the ACM 18, No. 12 (December 1975),
   pp. 683-696

--
Norman H. Cohen    ncohen@watson.ibm.com

Re: Exception Handling

[Bart Termorshuizen]

David B. Shapcott [C] wrote:
> 
> In article <32393072.72033128@shdgate.shd.de>,
> Felix Kasza <felixk@mailbag.shd.de> wrote:
> >Robbie,
> >
> > > replies by email please, i don't read this group.
> >
> >Not feeling very sociable today, are we?
> >
> > > Where did the concept of exception handling originate ?
> >
> >I don't know -- but I do know that IBM's /360 architecture uses a
> >mechanism for OS calls which looks very much like a trap.  PDPs used
> >similar features to handle illegal memory references.  In the late 60s
> >or early 70s, I saw an APL interpreter for the PDP that expressly made
> >use of this although it didn't export the functionality to the
> >programmer (APL has no concept of an exception).
> 
> I've heard that the Babbage Engine had an ingenious exception mechanism
> consisting of a cog and spring-loaded trip mechanism, that would activate
> a rod releasing a steel ball-brearing down a raceway.  The weight of the
> ball bearing was the value of the exception being thrown (for some time,
> Babbage had actually considered a throwing arm mechanism, but found that
> his mechanism could not be made accurate -- but this does provide an
> interesting historical account for the phrase `throwing an exception').
> 
> --
> D. Brad Shapcott [C]
> Contractor, Motorola Cellular Infrastructure Group

Way to go!  ;)
Bart.

Re: Exception Handling

[Rick Decker]

Paul A. Houle wrote:
> 
> Don't sweat it.  People on newsgroups treat each other like
> garbage.  This is because we can.  If people talked trash to each
> other the way that we do on USENET,  we'd see visual nonverbal
> signals of agression 

[like a punch in the mouth, f'r example]

>that would make us feel to distressed to
> continue.
> 
>         When the people on the other end of the connection are
> nothing more than a bit of badly written,  and these days,  badly
> formatted,  text sometimes you get to feel that people should get
> the death penalty for stupid posts,  unsolicited commerical spam
> and such.

Quite right.  One makes allowances for newbie behavior in the hope
that with time will come an understanding of, say, newsgroup netiquette.
What I find far more distressing is having to listen to people
who, after months and perhaps years, never manage to infer the rules
governing polite behavior.  Oh well, that's what killfiles are for, but
it's still regrettable.
> 
>         Another issue is that computer people are not good about
> attribution.  To take an example,  it seems clear that the advances
> in compiler technology from,  say,  the mid 60's to the mid 80's
> sprang from the lingustic discoveries of Noam Chomsky.  Most of the
> people who use the technology don't care.  In fact,  even CS
> academics don't talk about it much,  probably because they
> associate Noam Chomsky with the student protests of the 1960's
> and opposition to the Vietnam war.

Oh, golly.  Now I have to disagree.  First, for someone to choose 
deliberately to ignore Chomsky for his activities against the war would 
require (1) that these activities were known, which would likely mean 
the person would have to be at least as venerable as I am and (2) 
that the person would even find such behavior reprehensible in the first 
place.  No, I'd suggest that the liklier reasons would be that,
first, Chomsky's stuff is somewhat intimidating for a non-specialist, 
and, second, that there are quite a few derivative sources in CS 
literature that put transformational grammars and language hierarchies
in a much more familiar context.  I just did a quick scan of my 
bookshelves and of the sixteen books I have on theory and formal 
languages all sixteen mention Chomsky prominently.  I got bored before I 
finished my compiler texts, but at least the Dragon Book and Son of 
Dragon both contain citations of Chomsky.  Doesn't sound to me that 
he's *that* seriously ignored.
> 
>         I get the impression that people learn programming from
> copying other people's code.

I don't have a problem with that.  My guess is that if you were to ask
a collection of programmers how they learned that particular skill, a 
large fraction would admit to having spent a lot of time looking at the 
code other people produced.  After all, isn't that the way we all 
learned our first (and subsequent) natural language?  So why should 
learning a programming language be that much different?

>If book publishers were honest about
> it,  they'd write a book titled "Learn to Cut and Paste Java in
> 21 Hours!" 

If the title were a truthful statement of the contents, I'd buy it
in a second.  Even better, if I thought it could be done, I'd write
it myself and retire early.  Unfortunately, it's a hopeless task.  Even 
if you used a modern app builder, where the cutting and pasting is done 
by the program, no collection of canned code could possibly cover all 
the apps we would want to write.  The inevitable conclusion is that
no matter how many code exemplars we have available, we still have 
to know enough to wrap them up in a robust, correct program, which
is very good news for those of us in the ed biz.  That said, I'll
still reiterate my point that while on the road to learning how to 
program, examples can be very useful.

>People are more concerned with getting a program
> working fast than they are on attributing the source.

Good.  I get to end on a note of agreement, sort of.  I agree that
the general standards of citation could use some work.  The rules
differ slightly between real world programs and the sort of toy
programs students write, but not by much.  Getting a program working 
fast is a good thing.  Understanding what you're doing is even better,
and acknowledging publicly where the borrowed chunks came from is even 
better.


Regards,

Rick

-----------------------------------------------------
Rick Decker                   rdecker@hamilton.edu
Department of Comp. Sci.      315-859-4785
Hamilton College
Clinton, NY  13323            =  !=  ==  (!)
-----------------------------------------------------

Re: Exception Handling

[Robin Vowels]

	ncohen@watson.ibm.com (Norman H. Cohen) writes:

	>In article <323750EA.167E@maths.usyd.edu.au>, Robbie Gates
	><robbie@maths.usyd.edu.au> writes: 

	>|> Where did the concept of exception handling originate ? For example,
	>|> which languages were first to support this, or which papers first
	>|> proposed exception handling ?

The IBM System 360 (c. 1965) had an interrupt system that could
trap a range of computational conditions (division by
zero, floating-point overflow, fixed-point overflow,
floating-point underflow, loss of signficance, etc.
Such exceptions could be trapped by the OS, and a few
could be trapped by the user.  Such things
as protection exceptions were trapped by the OS.

Operating system service was initiated with an interrupt
generated by a user instruction SVC (SVC = SuperVisor Call).

THe S/360 probably extended the idea considerably over
what had appeared before.

Before that (c. 1961), the Burroughs B series would have
had protection and array subscript bound checking and whatever
else.  Perhaps someone can add something for that or other systems....

Re: Exception Handling

[Bob Halpern]

Robin Vowels wrote:
 
>         >|> Where did the concept of exception handling originate ? For example,
>         >|> which languages were first to support this, or which papers first
>         >|> proposed exception handling ?
> 
> The IBM System 360 (c. 1965) had an interrupt system that could
> trap a range of computational conditions (division by

There was hardware and software for exception handling that predated the
360.

The 7740 communications processor had several levels of interrupt
(exactly like
a PSW), had vectors to tell the software what happened (exactly like a
CSW),
additional PSWs for low storage, errors, etc.

Re: Exception Handling

[Thiago]

Robin Vowels wrote:
> 
>         ncohen@watson.ibm.com (Norman H. Cohen) writes:
> 
>         >In article <323750EA.167E@maths.usyd.edu.au>, Robbie Gates
>         ><robbie@maths.usyd.edu.au> writes:
> 
>         >|> Where did the concept of exception handling originate ? For example,
>         >|> which languages were first to support this, or which papers first
>         >|> proposed exception handling ?
> 
> The IBM System 360 (c. 1965) had an interrupt system that could
> trap a range of computational conditions (division by
> zero, floating-point overflow, fixed-point overflow,
> floating-point underflow, loss of signficance, etc.
> Such exceptions could be trapped by the OS, and a few
> could be trapped by the user.  Such things
> as protection exceptions were trapped by the OS.
> 
> Operating system service was initiated with an interrupt
> generated by a user instruction SVC (SVC = SuperVisor Call).
> 
> THe S/360 probably extended the idea considerably over
> what had appeared before.
> 
> Before that (c. 1961), the Burroughs B series would have
> had protection and array subscript bound checking and whatever
> else.  Perhaps someone can add something for that or other systems..UFMA - Brasil
Here the Java programming language are not an usual one. We use usually C++, VB, 
CLIPPER and DELPHI.

Re: Exception Handling

[Fritz Schneider]

Bob Halpern <wumpus@ix.netcom.com> wrote:

>Robin Vowels wrote:
> 
>>         >|> Where did the concept of exception handling originate ? For example,
>>         >|> which languages were first to support this, or which papers first
>>         >|> proposed exception handling ?
>> 
>> The IBM System 360 (c. 1965) had an interrupt system that could
>> trap a range of computational conditions (division by
>
>There was hardware and software for exception handling that predated the
>360.
>

The IBM 709 (a vacuum tube machine) introduced the concept of data
channels (now called DMA) in a commercial product ca. 1957. This
included interruptions, referred to in that architecture as traps. The
current instruction address was stored in a fixed location and control
was given to the channel trap routine which stored the registers and
processed the interruption. The instruction set included the TTR (TRAP
TRANSFER) instruction used to return from interruptions. It could not
be trapped, so the next interruption would occur back in the user
program rather than in the trap routine.
Fritz Schneider
Peacham Cybernetics
Sunnyvale, California
http://www.Peacham.com/~fritz/

Re: Exception Handling

[Robin Vowels]

	Fritz@Peacham.com (Fritz Schneider) writes:

	>Bob Halpern <wumpus@ix.netcom.com> wrote:
	>>Robin Vowels wrote:
	>>>         >|> Where did the concept of exception handling originate ? For example,
	>>>         >|> which languages were first to support this, or which papers first
	>>>         >|> proposed exception handling ?
	>>> 
	>>> The IBM System 360 (c. 1965) had an interrupt system that could
	>>> trap a range of computational conditions (division by
	>>
	>>There was hardware and software for exception handling that predated the
	>>360.

	>The IBM 709 (a vacuum tube machine) introduced the concept of data
	>channels (now called DMA) in a commercial product ca. 1957. This
	>included interruptions, referred to in that architecture as traps. The
	>current instruction address was stored in a fixed location and control
	>was given to the channel trap routine which stored the registers and
	>processed the interruption. The instruction set included the TTR (TRAP
	>TRANSFER) instruction used to return from interruptions. It could not
	>be trapped, so the next interruption would occur back in the user
	>program rather than in the trap routine.
	>Fritz Schneider >Peacham Cybernetics >Sunnyvale, California

Thanks for that info.

As far as DMA goes, the English Electric DEUCE computer
(c. 1955) performed asynchronous transfer between drum and
main memory.  I think that the ACE computer (c. 1950) did also.

Re: Exception Handling

[shmuel]

In <32529a13.6465307@nntp.netgate.net>, Fritz@Peacham.com (Fritz Schneider) writes:
>Bob Halpern <wumpus@ix.netcom.com> wrote:
>
>The IBM 709 (a vacuum tube machine) introduced the concept of data
>channels (now called DMA) in a commercial product ca. 1957. 

Sorry, but the data-channel trap feature of the 709 was not the first either. 
The earliest reference that I've seen to interrupts was on the 1103A, but I 
wouldn't put any money on it being first.

Re: Exception Handling

[Bob Halpern]

shmuel@os2bbs.com wrote:
> 
> In <32529a13.6465307@nntp.netgate.net>, Fritz@Peacham.com (Fritz Schneider) writes:
> >Bob Halpern <wumpus@ix.netcom.com> wrote:
> >
> >The IBM 709 (a vacuum tube machine) introduced the concept of data
> >channels (now called DMA) in a commercial product ca. 1957.
> 
> Sorry, but the data-channel trap feature of the 709 was not the first either.
> The earliest reference that I've seen to interrupts was on the 1103A, but I
> wouldn't put any money on it being first.

The SWAC had branching on overflow, negative, in the instruction. It
was built in the mid 50s, before the 709x, before the 650, before the
1103A (fine machine - shame Univac didn't realize it).

Re: Exception Handling - Test Please Ignore

[jekis]

Test Reply Only