[racket-dev] differences in error reporting

Sorry for the delay in getting back to you.

I think that what you're seeing here is just the imprecision in stack
traces that has to do with how Racket's optimizer works and how the
low-level stack (here by "low-level" I mean the approximate ones that are
coming from a low-level of the implementation as contrasted with the ones
that come when the "Debugging" radio button is selected in the language
dialog) traces work.

I can't explain why you see the source location some times and not other
times (I attribute that to the imprecision in the low-level stack traces)
but the reason you see something has to do with how DrRacket choses show a
stack location. It does this by looking at the exception. If it is a syntax
error, the location comes with the exception in a nice way and that gets
used (technically, it uses exn:srclocs? and associated machinery for this).
If not, then it looks for a stack that comes from the errortrace library
(this is what gets lost when you turn off debugging); if that stack is
present, it takes the first element of it. That's how you get precise
errors, ie in this program:

#lang racket
(define (f x) (+ 1 (car x)))
(f 11)

you'll see highlighting around the car expression directly.

If that's not there, the it uses the built-in stacks, again taking the
first one. This would get (probably) get you the function 'f' in the above
example and, I think, would always get it, if you defeat optimizations by
using this program:

#lang racket
(define (f x) (+ 1 (car x)))
(unless (zero? (random 1)) (set! f 12))
(f 11)

If none of those are around, you get no source location printed out.

Oh, and if the source location that you get from the above is the
definitions window, then it does not print out the name of the file; it
just puts the stop icon.

... I think that's all the relevant cases, but if you want, most of the
code is in error-display-handler/stacktrace in
collects/drracket/private/debug.rkt.

hth,
Robby



On Tue, Jan 29, 2013 at 8:21 PM, Pierpaolo Bernardi <olopierpa at gmail.com>wrote:

> AHA! You got it!
>
> It happens in the tabs which have 'No debugging...' checked, and
> doesn't happen otherwise.
>
>
> 2013/1/30, Robby Findler <robby at eecs.northwestern.edu>:
> > What is the "custom" part of the language settings you have on?
> >
> > Robby
> >
> >
> > On Tue, Jan 29, 2013 at 7:47 PM, Pierpaolo Bernardi
> > <olopierpa at gmail.com>wrote:
> >
> >> Update 2: it does not depend on buffer content.
> >>
> >> I have 9 tab open in this DrRacket. In 5 of them happen the strange
> >> message, in 4 of them it doesn't happen.
> >>
> >> I tried closing one in which it happened and then reopening the same
> >> file in a new tab, and in the new tab it doesn't happen.
> >>
> >>
> >> 2013/1/30, Robby Findler <robby at eecs.northwestern.edu>:
> >> > I don't see that with this program:
> >> >
> >> > #lang racket
> >> >
> >> > (define (integer->roman n)
> >> >   (cond ((not (integer? n))
> >> >          (raise-argument-error 'integer->roman "integer?" n))
> >> >         ((positive? n)
> >> >          (apply string-append n))
> >> >         ((negative? n)
> >> >          (apply string-append "NEGATIVVS " 1))
> >> >         (else
> >> >          "NVLLA")))
> >> >
> >> > Welcome to DrRacket, version 5.3.2.3--2013-01-29(32529d89/d) [3m].
> >> > Language: racket; memory limit: 128 MB.
> >> >> (integer->roman 3.3)
> >> > . . integer->roman: contract violation
> >> >   expected: integer?
> >> >   given: 3.3
> >> >> (integer->roman 3.3)
> >> > . . integer->roman: contract violation
> >> >   expected: integer?
> >> >   given: 3.3
> >> >>
> >> >
> >> >
> >> > On Tue, Jan 29, 2013 at 4:33 PM, Pierpaolo Bernardi
> >> > <olopierpa at gmail.com>wrote:
> >> >
> >> >> If I use raise-argument-error in my functions, like this:
> >> >>
> >> >> (define (integer->roman n)
> >> >>   (cond ((not (integer? n))
> >> >>          (raise-argument-error 'integer->roman "integer?" n))
> >> >>         ((positive? n)
> >> >>          (apply string-append (positive-integer->roman n)))
> >> >>         ((negative? n)
> >> >>          (apply string-append "NEGATIVVS " (positive-integer->roman
> (-
> >> >> n))))
> >> >>         (else
> >> >>          "NVLLA")))
> >> >>
> >> >> I get errors like this:
> >> >>
> >> >> Welcome to DrRacket, version 5.3.2.2--2013-01-26(88404f3/a) [3m].
> >> >> Language: racket [custom].
> >> >> > (integer->roman 3.3)
> >> >> integer->roman: contract violation
> >> >>   expected: integer?
> >> >>   given: 3.3
> >> >> > (integer->roman 3.3)
> >> >> . . C:\Program
> >> >>
> Files\Racket-Full-5.3.2.2\collects\racket\private\more-scheme.rkt:263:2:
> >> >> integer->roman: contract violation
> >> >>   expected: integer?
> >> >>   given: 3.3
> >> >>
> >> >> That is, from the second time on I get the extraneous prefix.  Is
> this
> >> >> expected?
> >> >>
> >> >> P.
> >> >>
> >> >>
> >> >> _________________________
> >> >>   Racket Developers list:
> >> >>   http://lists.racket-lang.org/dev
> >> >>
> >> >>
> >> >
> >>
> >> --
> >> Inviato dal mio dispositivo mobile
> >>
> >
>
> --
> Inviato dal mio dispositivo mobile
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.racket-lang.org/dev/archive/attachments/20130131/d05e9256/attachment.html>