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#lang at-exp racket/base
(require (only-in racket/format ~a)
"util.rkt")
(provide gui-required?
require-gui
txt/gui)
(define root-eventspace #f) ;#f until racket/gui/base required first time
(define (gui-required?)
(and root-eventspace #t))
;; Extra explanation for situations like issue 93, entering `(require
;; redex)` in the REPL, as opposed to having it in a .rkt file.
(define more-explanation
@~a{The namespace was reset. Any `require`s you entered in the REPL were "undone".
This includes the `require` you just entered. You may want to enter it again.})
;; This must be called from the main thread, under the main custodian!
(define (require-gui in-repl?)
(when (gui-required?)
(error 'require-gui "Already required"))
(display-commented "On-demand, one-time instantiation of racket/gui/base.")
(when in-repl?
(display-commented more-explanation))
(define current-eventspace (gui-dyn-req 'current-eventspace))
(define make-eventspace (gui-dyn-req 'make-eventspace))
(set! root-eventspace (make-eventspace))
(current-eventspace root-eventspace))
;; Like mz/mr from racket/sandbox.
(define-syntax txt/gui
(syntax-rules ()
[(_ txtval guisym)
(if (gui-required?)
(gui-dyn-req 'guisym)
txtval)]))
(define (gui-dyn-req sym)
(dynamic-require 'racket/gui/base sym))
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