Could I add a note like this to the docs for the indentation function?
“NB: indentation results depend on the graphical context associated with the
object; it may be necessary to associate the object with an editor-canvas and
frame in order to get the expected results."
That text might not actually be accurate…
John
> On Mar 20, 2020, at 1:16 PM, John Clements <cleme...@brinckerhoff.org> wrote:
>
> Ah! this solves the issue. many thanks.
>
>> On Mar 20, 2020, at 1:03 PM, Robby Findler <ro...@cs.northwestern.edu> wrote:
>>
>> Looks like you need a display or the text gets confused about how big
>> (in pixels) characters really are:
>>
>> #lang racket/gui
>> (require framework)
>> (define f (new frame% [label ""]))
>> (define t (new racket:text%))
>> (define ec (new editor-canvas% [parent f] [editor t]))
>> (send t insert "(+ 3\n4)")
>> (send t freeze-colorer)
>> (send t tabify-all)
>> (display (send t get-text))
>>
>> On Fri, Mar 20, 2020 at 2:12 PM John Clements <cleme...@brinckerhoff.org>
>> wrote:
>>>
>>> That actually solves a bunch of problems for me… but strangely, not the
>>> initial one. If, for instance, I tabify
>>>
>>> (+ 3
>>> 4)
>>>
>>> using the tabify-all method, the line with the four gets an indentation of
>>> 2, not 8. This is definitely different from DrRacket’s behavior.
>>>
>>> Any idea how to fix this?
>>>
>>> (cc:ing racket-users without permission, hope that’s okay?)
>>>
>>> John
>>>
>>>
>>>> On Mar 20, 2020, at 12:05 PM, John Clements <cleme...@brinckerhoff.org>
>>>> wrote:
>>>>
>>>> Ah! That’s probably a better solution, I’ll just do that. I searched for
>>>> “indent”, should I try to add that as a search term for the “tabify-all”
>>>> method?
>>>>
>>>> Many thanks!
>>>>
>>>> (Also, sending mail to the list using “us...@racket-lang.org” seems to be
>>>> broken right now for me, sigh.)
>>>>
>>>> John
>>>>
>>>>> On Mar 20, 2020, at 12:01 PM, Robby Findler <ro...@cs.northwestern.edu>
>>>>> wrote:
>>>>>
>>>>> I'm not sure of the details but did you consider just inserting it
>>>>> into a racket:text% and then calling the tabify-all method?
>>>>>
>>>>> Robby
>>>>>
>>>>> On Fri, Mar 20, 2020 at 1:26 PM John Clements <cleme...@brinckerhoff.org>
>>>>> wrote:
>>>>>>
>>>>>> Hmm… followup problem. If I try to indent the string “#|\nabc\n|#” (that
>>>>>> is, a block comment), the compute-racket-amount-to-indent method returns
>>>>>> #f. Is this a bug, or just undocumented behavior?
>>>>>>
>>>>>> John
>>>>>>
>>>>>>> On Mar 20, 2020, at 10:41 AM, John Clements <cleme...@brinckerhoff.org>
>>>>>>> wrote:
>>>>>>>
>>>>>>> I’m writing code to help me grade exams, and one of the issues I’ve run
>>>>>>> into is that the code coming out of the LMS is all totally unindented.
>>>>>>> So, for instance, a student’s response might read:
>>>>>>>
>>>>>>> ;Closures help a function value remember what substitutions have
>>>>>>> already been applied to it.
>>>>>>> '{vars {{x {lam {x} {+ 1 x}}}
>>>>>>> {y {lam {y} {+ 3 y}}}}
>>>>>>> {+ {x 2} {y 4}}}
>>>>>>>
>>>>>>> Obviously, it would be a lot easier to grade that if it was indented.
>>>>>>>
>>>>>>> Excellent! A chance to whip up a quick-and-dirty auto-indenter, using
>>>>>>> DrRacket’s indentation framework. Specifically, the
>>>>>>> `compute-racket-amount-to-indent` method of racket:text<%>.
>>>>>>>
>>>>>>> I’m pleased to report almost total success, aside from one strange
>>>>>>> off-by-one error that I’m looking for help with. To see it, here’s the
>>>>>>> result of my auto-indenter on the prior block:
>>>>>>>
>>>>>>> '{vars {{x {lam {x} {+ 1 x}}}
>>>>>>> {y {lam {y} {+ 3 y}}}}
>>>>>>> {+ {x 2} {y 4}}}
>>>>>>>
>>>>>>> (if you’re viewing this in a proportional-width font, that’s going to
>>>>>>> look terrible, sorry.)
>>>>>>>
>>>>>>> The issue is that the final plus line isn’t lined up with the
>>>>>>> curly-brace that’s two chars after the end of `vars`… instead, it’s one
>>>>>>> character to the left.
>>>>>>>
>>>>>>> A much simpler test case is simply running on “(+ 3\n4)”. Rather than
>>>>>>> getting the 4 lined up with the 3, I get it one character to the left.
>>>>>>>
>>>>>>> And… uh oh. A more illuminating test case occurs when I run my code on
>>>>>>> “(+ 3\n4)”. That is, I put a bunch more spaces before the 3. After
>>>>>>> indentation, the 4 is still only indented by two characters. So it
>>>>>>> looks like the `compute-racket-amount-to-indent` method is not looking
>>>>>>> for the token following the first one following the paren in the prior
>>>>>>> line (which would account for all the spaces), but just adding one to
>>>>>>> the last position of the first token following the paren. This makes me
>>>>>>> wonder whether DrRacket actually uses this method to indent.
>>>>>>>
>>>>>>> Hmm.
>>>>>>>
>>>>>>> Well, here’s the code to reproduce this. Note that there’s an obvious
>>>>>>> bug/assumption in that my code doesn’t account for any existing leading
>>>>>>> spaces on a line, but none of my examples have leading spaces following
>>>>>>> newlines.
>>>>>>>
>>>>>>> Advice appreciated!
>>>>>>>
>>>>>>> John
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> #lang racket
>>>>>>>
>>>>>>> (require framework)
>>>>>>>
>>>>>>> ;; given a string of racket text, return the corresponding indented
>>>>>>> string
>>>>>>> ;; NB: CURRENTLY ASSUMES ALL LINES START WITH ZERO SPACES.
>>>>>>> (define (string-indent text-to-indent)
>>>>>>> (define t (new racket:text%))
>>>>>>> (send t erase)
>>>>>>> (send t insert text-to-indent 0)
>>>>>>> (define num-paragraphs (add1 (send t last-paragraph)))
>>>>>>> (define indents
>>>>>>> (for/list ([n (in-range num-paragraphs)])
>>>>>>> (define par-start (send t paragraph-start-position n))
>>>>>>> (list par-start
>>>>>>> (send t compute-racket-amount-to-indent
>>>>>>> par-start
>>>>>>> head-sexp-type))))
>>>>>>> ;; NB: OBVIOUSLY WRONG, assumes all lines start with zero leading
>>>>>>> spaces:
>>>>>>> ;; act in reverse order, to avoid messing up the meaning of char posns:
>>>>>>> (for ([indent (in-list (reverse indents))])
>>>>>>> (send t set-position (first indent))
>>>>>>> (define space-string
>>>>>>> (list->string (for/list ([i (in-range (second indent))]) #\space)))
>>>>>>> (send t insert space-string))
>>>>>>> (send t get-text))
>>>>>>>
>>>>>>> ;; for now, always return 'other
>>>>>>> (define (head-sexp-type str)
>>>>>>> 'other)
>>>>>>>
>>>>>>>
>>>>>>> (define text-to-indent
>>>>>>> #<<|
>>>>>>> ;Closures help a function value remember what substitutions have
>>>>>>> already been applied to it.
>>>>>>> '{vars {{x {lam {x} {+ 1 x}}}
>>>>>>> {y {lam {y} {+ 3 y}}}}
>>>>>>> {+ {x 2} {y 4}}}
>>>>>>> |
>>>>>>> )
>>>>>>>
>>>>>>> (displayln (string-indent text-to-indent))
>>>>>>>
>>>>>>>
>>>>>>> (displayln (string-indent "
>>>>>>> (+ 3
>>>>>>> 4)"))
>>>>>>>
>>>>>>>
>>>>>>> (module+ test
>>>>>>> (require rackunit)
>>>>>>>
>>>>>>>
>>>>>>> (check-equal? (string-indent "
>>>>>>> (+ 3
>>>>>>> 4)")
>>>>>>> "
>>>>>>> (+ 3
>>>>>>> 4)")
>>>>>>>
>>>>>>> (check-equal? (string-indent "
>>>>>>> (+ 3
>>>>>>> 4)")
>>>>>>> "
>>>>>>> (+ 3
>>>>>>> 4)")
>>>>>>>
>>>>>>> (check-equal? (string-indent "
>>>>>>> (+ 3
>>>>>>> 4)")
>>>>>>> "
>>>>>>> (+ 3
>>>>>>> 4)"))
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>
>>>
>>>
>>>
>>
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