eliminated stateful variables from 16 year old code, and now I know it is correct
Closes PR 13074 set! sucks
This commit is contained in:
Matthias Felleisen
parent
b4fea2ff36
commit
93ca0bf9f7
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@ -1,4 +1,6 @@
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#lang racket/gui
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#lang racket
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(require racket/gui)
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;; ---------------------------------------------------------------------------------------------------
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;; functions that demonstrate how one and the same function can be used in three different contexts
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@ -112,19 +114,9 @@
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(inexact->exact x)
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(error 'convert OUT-ERROR x)))
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;; f2c : num -> num
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;; to convert a Fahrenheit temperature into a Celsius temperature
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(define (f2c f)
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(2int (* 5/9 (- f 32))))
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;; fahr->cel : num -> num
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;; student-supplied function for converting F to C
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(define (fahr->cel f)
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(error 'convert "not initialized"))
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;; slider-cb : slider% event% -> void
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;; slider-cb : (num -> num) object object -> [slider% event% -> void]
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;; to use fahr->cel to perform the conversion
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(define (slider-cb c s)
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(define ((slider-cb fahr->cel sliderC sliderF) c s)
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(send sliderC set-value
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((compose in-slider-range 2int fahr->cel)
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(send sliderF get-value))))
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@ -139,31 +131,31 @@
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#| --------------------------------------------------------------------
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view (exports sliderF sliderC SLI-MIN SLI-MAX) (imports f2c slider-cb)
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model (imports sliderF sliderC SLI-MIN SLI-MAX) (exports f2c slider-cb)
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view (exports SLI-MIN SLI-MAX) (imports slider-cb)
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parameter: sliderC sliderF
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model (imports SLI-MIN SLI-MAX) (exports slider-cb)
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----------------------------------------------------------------------- |#
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;; ============================================================================
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;; VIEW
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(define frame (make-object frame% "Fahrenheit to Celsius Conversion"))
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(send frame set-alignment 'center 'center)
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(define main-panel (instantiate horizontal-panel% () (parent frame)
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(stretchable-height #f)))
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;; convert-gui : (num -> num) -> void
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;; to install f as the temperature converter
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;; effect: to create a window with two rulers for converting F to C
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(define (convert-gui f)
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(check-proc 'convert-gui f 1 "convert-gui" "one argument")
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;; only initialize the slider based on the user's program when there aren't any exceptions.
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;; if there are exceptions, wait for the user to click "convert" to see an error.
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(define-values (sliderC frame) (make-gui f))
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(with-handlers ([exn:fail? (lambda (x) (void))])
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(send sliderC set-value (in-slider-range (f F-SLI-0))))
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(send frame show #t))
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;; create labels; aligned with sliders
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(define mpanel (make-object vertical-panel% main-panel))
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(let ()
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(make-object message% "Fahrenheit" mpanel)
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(make-object message% "" mpanel)
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(make-object message% "Celsius" mpanel)
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(void))
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(send mpanel stretchable-width #f)
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(define panel (make-object vertical-panel% main-panel))
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(send panel set-alignment 'center 'center)
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;; f2c : num -> num
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;; to convert a Fahrenheit temperature into a Celsius temperature
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(define (f2c f) (2int (* 5/9 (- f 32))))
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(define F-SLI-MIN -50)
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(define F-SLI-MAX 250)
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@ -171,42 +163,45 @@
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(define SLI-MIN (f2c F-SLI-MIN))
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(define SLI-MAX (f2c F-SLI-MAX))
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;; sliderF : slider%
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;; to display the Fahrenheit temperature
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(define sliderF (make-object slider% #f F-SLI-MIN F-SLI-MAX panel void F-SLI-0))
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(send sliderF min-width (- F-SLI-MAX F-SLI-MIN))
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;; sliderC : slider%
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;; to display the Celsius temperature
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(define sliderC (make-object scale% panel))
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(define _set-sliderC (send sliderC set-value (in-slider-range (f2c F-SLI-0))))
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(define button-panel (instantiate vertical-panel% ()
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(stretchable-width #f)
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(stretchable-height #f)
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(parent main-panel)))
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;; convert : button%
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;; to convert fahrenheit to celsius
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(define convert (make-object button% "Convert" button-panel slider-cb))
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(define close (make-object button% "Close" button-panel
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(lambda (x e) (send frame show #f))))
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;; convert-gui : (num -> num) -> void
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;; to install f as the temperature converter
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;; effect: to create a window with two rulers for converting F to C
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(define (convert-gui f)
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(check-proc 'convert-gui f 1 "convert-gui" "one argument")
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(set! fahr->cel f)
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;; only initialize the slider based on the user's program
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;; when there aren't any exceptions.
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;; if there are exceptions, wait for the user to click
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;; "convert" to see an error.
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(with-handlers ([exn:fail? (lambda (x) (void))])
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(send sliderC set-value (in-slider-range (fahr->cel F-SLI-0))))
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(send frame show #t))
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(define (make-gui fahr->cel)
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(define frame
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(parameterize ((current-eventspace (make-eventspace)))
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(new frame%
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[label "Fahrenheit to Celsius Conversion"]
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[alignment '(center center)])))
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(define main-panel
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(new horizontal-panel% [parent frame] [stretchable-height #f]))
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;; create labels; aligned with sliders
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(define mpanel (make-object vertical-panel% main-panel))
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(make-object message% "Fahrenheit" mpanel)
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(make-object message% "" mpanel)
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(make-object message% "Celsius" mpanel)
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(send mpanel stretchable-width #f)
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(define panel (make-object vertical-panel% main-panel))
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(send panel set-alignment 'center 'center)
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;; sliderF : slider%
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;; to display the Fahrenheit temperature
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(define sliderF (make-object slider% #f F-SLI-MIN F-SLI-MAX panel void F-SLI-0))
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(send sliderF min-width (- F-SLI-MAX F-SLI-MIN))
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;; sliderC : slider%
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;; to display the Celsius temperature
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(define sliderC (make-object scale% panel))
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(define _set-sliderC (send sliderC set-value (in-slider-range (f2c F-SLI-0))))
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(define button-panel
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(new vertical-panel% (stretchable-width #f) (stretchable-height #f) (parent main-panel)))
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;; convert : button%
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;; to convert fahrenheit to celsius
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(make-object button% "Convert" button-panel (slider-cb fahr->cel sliderC sliderF))
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(make-object button% "Close" button-panel (lambda (x e) (send frame show #f)))
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(values sliderC frame))
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;; ============================================================================
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;; convert-repl : (num -> num) -> void
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@ -257,7 +252,7 @@
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(with-handlers ((exn:fail:read? (lambda (y) (raise x))))
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(convert-file
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(lambda ()
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(unless (htdp-file-prefix? (current-input-port)) (raise x)))))]
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(unless (htdp-file-prefix? (current-input-port)) (raise x)))))]
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[else (raise x)]))))
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(convert-file void)))
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@ -1,4 +1,4 @@
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#lang scheme
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#lang racket
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(require htdp/testing)
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(require htdp/convert)
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@ -35,11 +35,11 @@
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(convert-file IN f2c OUT)
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(with-input-from-file OUT check-convert-out)
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(check-error (convert-file IN list OUT) "convert: The conversion function must produce a number; but it produced (212)")
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(check-error (convert-file IN list OUT) "convert: The conversion function must produce a number; but it produced '(212)")
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(check-error (convert-file IN first OUT) "first: expected argument of type <non-empty list>; given 212")
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(check-error (convert-file IN first OUT) "first: expects non-empty list; given 212")
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(check-error (convert-file IN fx OUT) "convert: The conversion function must produce a number; but it produced xyz")
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(check-error (convert-file IN fx OUT) "convert: The conversion function must produce a number; but it produced 'xyz")
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(check-error (convert-file IN f2c 10) "convert-file: expects a string as third argument, given 10")
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@ -54,7 +54,8 @@
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(convert-gui f2c)
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(define (f2x x) (* x x x x))
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;; (convert-gui f2x)
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(convert-gui f2x)
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;; must result in an error
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;; TEST BY HAND: (convert-gui first)
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