don't use callbacks, but two submit-buttons
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parent
74acc71447
commit
d690a7a24e
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@ -7,7 +7,7 @@
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scheme)
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(begin
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;; This uses callbacks.
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;; This doesn't use callbacks anymore.
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(define *operator-alist*
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`(("+" . ,+)
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@ -33,15 +33,6 @@
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`(option ,(operator-symbol operator)))
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*operator-alist*)))))
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(define (change-operator-callback)
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(make-callback
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(lambda (req)
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(change-operator
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;; This yields an error only when the browser doing wrong.
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(input-field-value operator-input-field
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(get-bindings req))))
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))
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(define (make-number-input-field/default default)
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(if default
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@ -52,6 +43,8 @@
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(let* ((update-text (:optional maybe-update-text ""))
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(number-field1 (make-number-input-field/default number1))
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(number-field2 (make-number-input-field/default number2))
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(calculate-button (make-submit-button "Calculate"))
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(change-button (make-submit-button "Change operator"))
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(req
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(send-html/suspend
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(lambda (new-url)
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@ -67,34 +60,42 @@
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(td ,(operator-symbol operator-pair))
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(td ,number-field2)
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(td " = ")
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(td ,(make-submit-button '(@ (value "calculate")))))))
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(hr)
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(p "You may choose another operator:")
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(servlet-form
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,(change-operator-callback)
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(td ,calculate-button)))
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(hr)
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(p "You may choose another operator:")
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(table
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(tr (td ,operator-input-field)
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(td ,(make-submit-button
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'(@ (value "change operator"))))))))))))
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(td ,change-button)))))))))
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(bindings (get-bindings req)))
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(let ((number1
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(with-fatal-error-handler
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(lambda (c d) #f)
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(input-field-value number-field1 bindings)))
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(number2
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(with-fatal-error-handler
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(lambda (c d) #f)
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(input-field-value number-field2 bindings))))
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(if number1
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(if number2
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(calculate operator-pair number1 number2)
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(show-page operator-pair number1 number2 "Please enter a valid second number."))
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(show-page operator-pair number1 number2 "Please enter a valid first number."))
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)))
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(cond
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((input-field-binding calculate-button bindings)
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(let ((number1 (with-fatal-error-handler
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(lambda (c d) #f)
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(input-field-value number-field1 bindings)))
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(number2 (with-fatal-error-handler
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(lambda (c d) #f)
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(input-field-value number-field2 bindings))))
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(if number1
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(if number2
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(calculate operator-pair number1 number2)
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(show-page operator-pair number1 number2
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"Please enter a valid second number."))
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(show-page operator-pair number1 number2
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"Please enter a valid first number."))))
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((input-field-binding change-button bindings)
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(with-fatal-error-handler
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(lambda (c d)
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;; This should never happen.
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(show-page operator-pair #f #f
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"Internal error. Please retry or report."))
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(show-page (input-field-value operator-input-field
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bindings)
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#f #f)))
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(else
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;; This should never happen.
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(show-page operator-pair #f #f
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"Internal error. Please retry or report.")))))
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(define (change-operator to-operation)
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(show-page to-operation #f #f))
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(define (calculate operator-pair number1 number2)
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(let ((operator (operator-operator operator-pair)))
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(show-result number1 (operator-symbol operator-pair) number2
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